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Saprolegnia, Achlya, Pythiopsis, Dictyuchus, A plones. Motile zoospores a ycast, and even bring about alcoholic fermentation in a saccharine which escape from the zoosporangium are present except in A planes. solution. Thc sexual reproduction shows all transitions between sorms which The segments of the hyphae in this group usually contain several are normally sexual, like the Peronosporaceae, to forms in which nuclei. At the time of sporangial formation the protoplasm with no antheridium is developed and the oospheres develop partheno- numerous nuclei streams into the swollen end of the sporangiophore genetically. The oogonia, unlike thc Peronosporaccae, contain more and there becomes cut off by a cell-wall to form the sporangium. than one oosphere. Klebs has shown that the development of The protoplasm then becomes cut up by a series of clefts into a zoosporangia or of oogonia and pollinodia respectively in Saprolegnia number of smaller and smaller pieces which are unicellular in is dependent on the external conditions; so long as a continued Pilobolus, multicellular in Sporodinio. These then become surstream of suitable food-material is ensured the mycelium grows on rounded by a cell-wall and form the spores. This mode of sporewithout forming reproductive organs, but directly the supplies of formation is totally different from that in the ascus; hence one of nitrogenous and carbonaceous food fall below a certain degrce of the difficulties of the acceptance of Brefeld's view of the homology concentration sporangia are developed. Further reduction of the of ascus and sporangium. The cytology of zygospore-formation is supplies of food effects the formation of oogonia. This explains the known in detail; sequence of events in the case of a Saprolegnia-mycelium radiating the so-called gametes from a dead fly in water. Those parts nearest the fly and best which suse are multisupplied develop barren hyphae only; in a zone at the periphery, nucleate and are no doubt where the products of putrefaction dissolved in the water form a of the nature of game dilute but easily accessible supply, the zoosporangia are developed tangia. The fate of these in abundance; oogonia, however, are only formed in the depths of nuclei is doubtful, probthis radiating mycelium, where the supplics of available food ably they fuse in pairs materials are least abundant.

(fig. 6). Chytridineae. --These parasitic and minute, chiefly aquatic, forms Blakeslee has lately may be looked upon as degenerate Oomycetes, since a sexual process made some very importand fecble unicellular mycelium occur in some; or they may be ant observations of the regarded as series of primitive forms leading up to higher members. Zygomycetes. It is well There is no means of deciding the question. They are usually known that while in some. included in Oomycetes, but their simple structure, minute size, forms, e.g. Spordinia, usually uniciliate zoospores, and their negative characters would zygospores are easily objustify their retention as a separate group. It contains less than tained, in others, e.g. most 200 species, chiefly parasitic on or in algae and other water-plants species of Mucor, they or animals, of various kinds, or in other lungi, secdlings, pollen and are very erratic in their higher plants. They are often devoid of hyphac, or put forth fine appearance. This has now protoplasmic filaments into the cells of their hosts. After absorbing been explained by the cell-contents of the latter, which it does in a few hours or days, Blakcslee, who finds that the fungus puts out a sporangium, the contents of which break up the Mucorinae can be into numerous minute swarm-spores, usuaily one-ciliate, rarely divided into two groups, two-ciliate. Any one of these soon comes to rest on a host-cell, termed homothallic and and either pierces it and cmptics its contents into its cavity, where heterothallic respectively.'s :) the further development occurs (Olpidium), or merely sends in In the first group zygodelicate protoplasmic filaments (Rhizophydium) or a short hyphal | spores can arise by the tube of, at most, two or three cells, which acts as a haustorium, union of branches from the further development taking place outside the cell-wall of the the same mycelium and host (Chytridium)." In some cases resting spores are formed inside so can be produced by the the host" (Chytridium), and give rise to zoosporangia on germina- growth from a single sporc; tion. In a few species a sexual process is described, consisting in this group includes Spor. the conjugation of similar cells (Zygochytrium) or the union of dinis grandis, Spinellus permission of Gustav Fischer.

From Strasburger's Lehrbuch da Botanik, by two dissimilar ones. (Polyphagus). In the development of dis- fusiger, some species of

FIG. 6.- Mucor Mucedo. tinct antheridial and oogonial cells the allied Ancylistineae show Mucor, &c. The majority

Different close alliances to Pythium and the Oomycetes. On the other hand, of forms, however, fall stages in the formation and germinathe uniciliate zoospores of Polyphagus have slightly amoeboid | into the heterothallic

tion of the zygospore. (Aster Brefeld, movements, and in this and the pseudopodium-like nature of the group, in which the asso. 1-4. 5 from v. Tavel, Pilze.) protoplasmic processes, such forms suggest resemblances to the ciation of branches from Myxomycetes. Opinions differ as to whether the Chytridineae are de- two mycelia different in 1. Two conjugating branches in contact. graded or primitive forms, and the group still needs critical revision. nature is necessary for the 2, Septation of the conjugating cells (a) Many new forms will doubtless be discovered, as they are rarely formation of zygospores.

from the suspensors (b), collected on account of their minuteness. Some forms cause damping These structures cannot 3, More advanced stage, the conjugatoff of seedlings-e.g. Olpidium Brassicae; others discoloured spots then be produced from the

ing cells (a) are still distinct from and even tumour-like swellings--e.g. Synchylium Scabrosaes. product of a single spore

one another; the warty thickenings Succisae, Urophlyctis, &c., on higher plants. Analogies have been nor even from the thalli of their walls have commenced to pointed out between Chytridiaceae and unicellular algae, such as derived from any two

form, Chlorosphaeraceae. Protococcaccae, “ Palmellaceae."

&c., some of spores. The two kinds of 4. Ripe zygospore. (b) between the sus. which are parasitic, and suggestions may be entertained, as to thalli Blakeslce considers

pensors (a). possible origin from such algae.

to have a differentiation 5, Germinating zygospore with a germThe Zygomyceles, of which about 200 species are described, are of the nature of sex and tube bearing a sporangium, especially important from a theoretical standpoint, since they fur. he distinguishes them as (+) and (-) forms; the former being nished the series whence Breseld derived the vast majority of the usually distinguished by a somewhat greater luxuriance of growth. fungi. They are characterized especially by the zygospores, but The classification of the Mucorini depends on the prevalence and the asexual organs (sporangia) exhibit interesting series of changes, characters of the conidia, and of the sporangia and zygospores.8 beginning with the typical sporangium of Mucor containing numerous the presence or absence of a columella in the former, the formation endospores, passing to cases where, as in Thamnidium, these are of an investment round the latter. Most genera are saprophytes, accompanied with more numerous small sporangia (sporangioles) but some-Chaetocladium, Piplocephalis-are parasites on other containing few spores, and thence to Chaetocladium and Piplocephalis, Mucorini, and one or two are associated casually with the rotting where the sporangioles form but one spore and fall and germinate of tomatoes and other fruits, bulbs, &c., the Aeshy parts of which as a whole; that is to say, the monosporous sporangium has become are rapidly destroyed if once the hyphae gain entrance. Even more a conidium, and Brefeld regarded these and similar series of changes important is the question of mycosis in man and other animals, as explaining the relation of ascus to conidium in higher fungi. referred to species of Mucor, and investigated by Lucet and Co According to his view, the ascus is in effect the sporangium with stantin. Klebs has concluded that transpiration is the important several spores, the conidium the sporangiole with but one spore, factor in determining the formation of sporangia, while zygote and that not loose but fused with

the sporangiole wall. On this development depends on totally different conditions; these results basis, with other interesting morphological comparisons. Brefeld have been called in question by Falck. erected his hypothesis, now untenable, that the Ascomycetes and The Entomophthoraceae contain three genera, Empusa, Enio Basidiomycetes diverge from the Zygomycetes, the former having mophthora and Basidiobolus. The two first genera consist of forms particularly specialized the ascus (sporangial) mode of reproduction, which are parasitic on insects. Empusa Muscae causes the wellthe latter having specialized the conidial (indehiscent one-spored known epidemic in house-Aics during the autumn; the dead, affected sporangiole) mode. In addition to sporangia and the conidial spores Aies are often found attached to the window surrounded by a white referred to some Mucorini show a peculiar mode of vegetative halo of conidia. B. ranorum is found in the alimentary canal of the reproduction by means of gemmae or chlamydospores-.e. short frog and growing on its excrement. In these three genera the conidia segments of the hyphac become stored with fatty reserves and act are cast off with a jerk somewhat in the same way as the sporangium as spores. The gemmae formed on submerged Mucors may bud like 'of Pilobolusi

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B. HIGHER FUNGI.--Now that Brefeld's view of the origin | 32 and 64, &c.; in a few cases the number of spores is less than of these forms from the Zygomycetes has been overthrown, eight by abortion of some of the eight nuclei. The ascus is thus one the relationship of the higher and lower forms of fungi is left of the most sharply characterized structures among the fungi. in obscurity. The term Eumyceles is sometimes applied to this (Sphaerotheca, Pyronema, &c.), in others the antheridium is abortive group to distinguish them from the Phycomycetes, but as the or absent, but the ascogonium (gogonium) is still present and the same name is also applied to the fungi as a whole to differentiate female nuclei fuse in pairs (Lachnea them from the Mycetozoa and Bacteria, the term had best be bolus furfuraceus):

slercorea, Humaria granulata, Asco

while in other dropped. The Higher Fungi fall into three groups: the Ustic forms ascogonium and antheridium laginales, of doubtful position, and the two very sharply marked are both absent and fusion occurs groups Basidiales and Ascomycetes.

between vegetative nuclei (Humaria 1. Ustilaginales.---This includes two families Ustilaginaceae of other forms). In other cases the

rutilans, and probably the majority (smuts) and Tilletiaceae (bunts). The bunts and smuts which sexual fusion is apparently absent damage our grain and fodder plants comprise about 400 species of altogether, as in Exoascus. In the first internal parasites, found in all countries on herbaceous plants, and

case (fig. 9) we have a true sexual especially on Monocotyledons. They are remarkable for their dark

process, while in the second and third spores developed in gall-like excrescences on the leaves, stems, &c.,

cases we have a reduced sexual process or in the fruits of the host. The discovery of the yeast-conidia of in which the fusion of other nuclci these fungi, and their thorough investigation by Brefeld, have

has replaced the fusion of the normal thrown new lights on the group, as also have the results elucidating male and female nuclei. It is to be the nature of the ordinary dark spores-smuts, bunt, &c.—which by noted that all the forms exhibit the their mode of origin and development are chlamydospores. When fusion of nuclei in the ascus, so that

B the latter germinate a slender" promycelium " is put out; in those with the normal or reduced From Strasburger's Lehrbuch der Ustilago and its allies this is transversely septate, and bears lateral sexual process described above have Botanik, by permission of Gustav conidia (sporidia); in Tilleria and its allies non-septate, and bears two nuclear fusions in their life. Fischer, a terminal tust of conidia (sporidia) (fig. 7); Brefeld regarded the history. The advantage or signifi. Fig. 8.—Development of the promycelium as a kind of basidium, bearing lateral or terminal cance of the second (ascus) fusion is

Ascus.
conidia (comparable to basidio-
not clearly understood.

A-C, Pyronema confluens.
spores), but since the number of
The group of the Hemiasci was

(After Harper.) basidiospores is not fixed, and the rounded by Brefeld to include forms D, Young , ascus of Boubasidium has not yet assumed very which were supposed to be a connect.

diera with eight spores. definite morphological characters, ing link between Phycomycetes and

. Brefeld termed the group Hemi- Ascomycetes. As mentioned before, basidii, and regarded them as a hall- the connexion between these two groups is very doubtlul, and the deway stage in the evolution of the rivation of the ascus from an ordinary sporangium of the Zygomycetes true Basidiomycetes from Phycomycetes, the Tillelia type leading included in this group have been shown to be either true Phycomycetes

cannot be accepted. The majority of the forms which were formerly to the truc basidium (Autobasidium), (like A scoidea) or true Ascomycetes (like Thelebolus), Eremascus and

the. Uslilago, type to the proto-Dipodascus, which are often placed among the Hemiasci, possibly do pm

basidium, with lateral spores; but this
view is based on very poor evidence,

not belong to the Ascomycetes series at all.
so that it is best to place these forms include Exoescus, Taphrina, A scorlicium and Endomyces.
Eroascaceae are a small group of doubtful extent here used to

The as a separate group, the Uslilagınales.

The yeast-conidia, which bud off
B. from the conidia or their resulting

mycelium when sown in nutrient From Vine's Students' Text Book of solutions, are developed in succesBolany, by permission of Swan Sonnen- sive crops by, budding exactly as

in the yeast plant, but they cannot Fig. 7:-Germinating resto ferment sugar solutions. It is the ing-gonidia. A, of Ustilago rapid spread of these yeast-conidia rece placulorum; B, of Tilletia in manure and soil waters which Caries.

makes it so difhcult to get rid of sp The gonidium.

smuts, &c., in the fields, and they, pm, The promycelium. like the ordinary conidia, readily d. The sporidia: in B the infect the seedling wheat, oats,

sporidia have coalesced barley or other cereals. Infection in pairs at v.

in these cases occurs in the secdling

at, the place where root and shoot meet, and the infecting hypha having entered the plant goes on living in it and growing up with it as if it had no parasitic action at all

. When the flowers form, however, the mycelium sends hyphae into the young ovaries and rapidly replaces the stores of sugar and starch, &c., which would have gone to make the grain, by the soot-like mass of

From Strasburger's Lehrbuch der Baranik, by permission of Gustav Fischer. spores so well known as smut, &c. These spores adhere to the grain, Fig. 9.-Sphaerolheca Castagnei. Fertilization and Development and unless destroyed, by " steeping" or other treatment, arc sown

of the Perithecium. (After Harper.) with it, and again produce sporidia and yeast-conidia which infect the seedlings. In other species the infection occurs through the

1. Oogonium (og) with the an- 5. Fertilized oogonium style of the flower, but the fungus after reaching the ovule develops

theridial branch (as) applied rounded by two layers of

to its surface. no further during that year but remains dormant in the embryo

hyphae derived from the of the seed. On germination, however, the fungus behaves in the

stalk-cell (st).
2. Separation of antheridium
(an).

6. The multicellular ascogonium same way as one which has entered in the seedling stage. The cytology of these forms is very little known; Dangcard states that

3. Passage of the antheridial, derived by division from the

nucleus towards that of the there is a fusion of two nuclei in the chlamydospore, but this requires

oogonium; the terminal cell confirmation. Apart from this observation there is no other trace

oogonjum.

with the two nuclei (as)

4, of sexuality in the group.

Union of the nuclei.

gives rise to the ascus. II. A scomyceles. This, except in the case of a few of the simpler forms, is a very sharply marked group characterized by a special mycelium is very much reduced in extent. The asci are borne type of sporangium, the ascus. . In the development of the ascus we directly on the mycelium and are therefore fully exposed, being find two nuclei at the base which fusc together to form the single devoid from the beginning of any investment. The Taphrineae, nucleus of the young ascus. The single nucleus divides by three which include Exoascus and Taphrina, are important parasites successive divisions to form cight nuclei lying free in the protoplasmc.g. pocket-plums and witches' brooms on birches, &c., are due to of the ascus. Then by a special method, described first by Harper, their action (fig. 10). Exoascus and A scorticium present interesting a mass of protoplasm is cut out round each nucleus; thus cight parallels to Exobasidium and Corlicium among the Basidiomycetes. uninucleate ascosporcs are formed by frce-cell formation. The Saccharomycelaccae include the well-known yeasts which belong protoplasm remaining over is termed epiplasm and often contains mainly to the genus Saccharomyces. They are characterized by glycogen (fig. 8). In some cases nuclear division is carried further their unicellular nature, their power of rapid budding, their capacity before spore formation occurs, and the number of spores is then 16, ! for fermenting various sugars, and their power of forming endogenous

an

schein & Co.

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spores. The sporangium with its endogenous spores has been | and others have shown that a ferment (zymase) can be extracted compared with an ascus, and on these grounds the group is placed from yeast-cells which causes sugar lo break up into carbon dioxide among the Ascomycetes-a very doubilul association. The group and alcohol. It has since been shown by Buchner and Albert that has attained an importance of laic even beyond that to which it was yeast-cells which have been killed by alcohol and ether, or with brought by Pastcur's researches on alcoholic fermentation, chiefly acetonc, still retain the enzyme. Such material is far more active owing to the exact results of the investigations of Hansen, who than the zymase obtained originally by Buchner from the expressed first applied the methods of pure cultures to the study of these juice of yeast-cells. Thus alcoholic fermentation is brought into

line organisms, and showed that many of the inconsistencies hitherto with the other formentations.

existing in the literature were Schizosaccharomyces includes a few species in which the cells do
due to the coexistence in the not "bud " but become clongated and then divide transversely,
cultures of several species or In the formation of sporangia two cells fuse together by means of
races of yeasts morphologically outgrowths, in a manner very similar to that of Spirogyra; sometimes,
almost indistinguishable, but however, the wall between two cells merely breaks down. The
physiologically very different. lused cell becomes a sporangium, and in it eight spores are developed.
About fifty species of Saccharo- In certain cases single cells develop parthenogenetically, without
myces are described more or less fusion, cach cell producing, however, only four spores. In 2ygo-
completely, but since many of saccharomyces described by Barker (1901) we have a form of the
these cannot be distinguished usual sprouting type, but here again there is a fusion of two cells to
by the microscope, and some form a sporangium.
have been found to develop Cytology.-The study of the nucleus of yeast-cells is rendered
physiological races or varieties difficult by the presence of other deeply staining granules termed by
under special conditions of Guillermond metachromatic granules. These have often becn mis.

growth, the limits are still far taken for nuclei and have to be carclully distinguished by differential .cat

ill-defined for complete stains. In the process of buddling the nucleus divides apparently -ep

botanical treatment of the genus. by a process of direct division. In the formation of spores the nucleus A typical yeast is able to develop of the cell divides, the protoplasm collects round the nuclei to form new cells by budding when sub- the sporcs by free-cell formation; the protoplasm (epiplasm) not merged in a saccharine solution, used in this process becomes disorganized. A fusion of nuclei was

and to ferment the sugar.e. originally described by Jansens and Leblanc, but it was observed From Strasburger's Lehrbuch der Botanik, by permission of Gustav Fischer,

so to break up its molecules that, neither by Wager nor Guillermond and is probably absent. In

apart from small quantities used Schizosaccharomyces and Zygosaccharomyces, however, we have a Fig. 10.-Taphrina Pruni: for its own substance, masses of fusion of nuclei in connexion with the conjugation of cells which Transverse section through the it out of all proportion to the precedes sporangium-formation. The theory may be put forward epidermis of an infected plum. mass of ycast used become ihat the ordinary forms have been derived from sexual forms like Four ripe asci, ai, az, with cight resolved into other bodies, such Schizosaccharomyces and Zygosaccharomyces by a loss of sexuality, spores, as,.a.. with yeast-like conidia abstricted from the spores. the process requiring little or as carbon dioxide and alcohol, the sporangium being formed parthenogenetically without any

nuclear fusion. This suggests a possible relationship to Eremascus, Alter Sadebeck.

no oxygen. Brefeld regards the which can only doubtfully be placed in the Ascomycetes (vide supra). sl, Stalk-cells of the asci. m, Filaments of the mycelium tion of conidia.

budding process as the forma- Carpoascomycetes. The other divisions of the Ascomycetes may

Under other be distinguished as Carpoascomycetes because they do not bear cut transversely.

conditions, of which the tempera- the asci free on the mycelium but enclosed in definite fruit bodies cul, Cuticle.

ture is an important one, the or ascocarps. The ascocarps can be distinguished into two portions, ep. Epidermis.

nucleus in the yeast-cell divides, a mass of sterile or vegetative hyphae forming the main mass of the

and cach daughter-nucleus again, fruit body, and surrounding the seriile ascogenous hyphae which and four spores are formed in the mother cell, a process obviously com- bear at their ends the asci. When the ascogonium (female organ) parable to the typical development of ascospores in an ascus. Under is present the ascogenous hyphae arise from it, with or without its yet other conditions the quiescent yeast-cells floating on the surface previous susion with an antheridium. In other cases the ascogenous of the fermented liquor grow out into elongated sausage-shaped or hyphae arise directly from the vegetative hyphae. In connexion cylindrical cells and branching cell-series, which mat together into with this condition of reduction a fusion of nuclei has been observed mycelium-like veils. At the bottom of the sermented liquor the in Humaria rullans and is probably of frequent occurrence. The cells often obtain fatty contents and thick walls, and behave as asci may be derived from the terminal cell of the branches of the resting cells (chlamydospores). The characters employed by experts ascogenous hyphae, but usually they are derived from the penfor determining a species of yeast are the sum of its peculiarities as ultimate cell, the tip curving over to form the so-called crozier. By regards form and size: the shapes, colours, consistency, &c., of this means the ascus cell is brought uppermost, and after the fusion the colonies grown on certain dcfinite media; the optimum tem- of the two nuclei it develops enormously and produces the ascospores. perature for spore formation, and for the development of the The ascospores escape

from the asci in various ways, sometinics by veils "; and the behaviour as regards the various sugars.

a special ejaculation-mechanism. The Ascomycetes, at least the The following .summary of some of the principal characteristics Carpoascomycetes, exhibit a well-marked alternation of sexual and of half-a-dozen species will serve to show how such peculiarities can asexual generations. The ordinary mycelium is the gametophyte be utilized for systematic purposes:

since it bears the ascogonia and antheridia when present; the Species. Optimum Temperature (or

Characters of

Sugars Fermented and Spores. Veils. Fermentation. Cells. Spores.

Products, &c
S. cereviseae I.

20-28°
High Rounded Globoid

Inverts maltose and sacS. Pastorianus I.

27-5°
26-28°

Low
Rounded Globoid

charose and for alcohol S. ellipsoideus

33o-34°

Low
Rounded Gluboid

4-6 vol.%. S. anomalus

?
High

Ditto, and evolves a fra.
Elliptical Hat-shaped

grant et her. S. Ludwigii

30°-31°

?

? Elongated Globoid Will not invert maltose. S. membranaefaciens

High Elongated Globoid

Inverts ncither maltose nor

saccharose, Two questions of great theoretical importance have been raised ascugenous hyphae with their asci represent the sporophyte

since over and over again in connexion with ycasts, namely: (1) the they are derived from the fertilized ascogonium. ' The matter is morphological one as to whether yeasts are merely degraded forms complicated by the apogamous transition from çamciophyte to of higher fungi, as would seem implied by their tendency to form sporophyte in ihe absence of the ascogonium; also by the fact that elongated, hypha-like cells in the veils, and their development there are normally two fusions in the life-history as mentioned of "ascospores" as well as by the wide occurrence of yeast-like carlict. If there are two fusions one would expect two reductions,

sprouting forins in other fungi (e.g. Nucor, Exoasci, Ustilagineae, and Harper has suggested that the division of ihe nuclei into eight higher Ascomycetes and Basidiomycetes); and (2) the question as

in the ascus, instead of into four spores as in most reduction proto the physiological nature and meaning of fermentation. With cesses, is associated with a double reduction process in the ascus. regard to the first question no satisfactory proof has as yet been Miss Fraxt in llumaria rutilans finds two reductions: a normal given that Saccharomycetes are derivable by culture from any synaptic reduction in the first nuclear division of the ascus, and a higher form, the recent statements to that effect not having been peculiar reduction division termed brachymeiosis in the third ascus confirmed. At the same time there are strong grounds for insisting division. on the resemblances between Endomi yees, a hyphal fungus bearing Various types of ascocarp are characteristic of the different yeast-like asci, and such a form as Saccharomyces anomalus. Con divisions of the Carpoascomycetes: the ckistothecium, apothecium cerning the second question, the recent investigations of Buchner and perisherium.

30

280

31°

30°

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e Perisporinese. This includes two chief families, Erysiphaceae characterized in general by the possession of an ascocarp which, and Pcrisporiaceae. They are characterized by an ascocarp without though usually a completely closed structure during the earlier any opening to the exterior, the ascospores being set free by the stages of development, at maturity opens out to form a bowl or decay or rupture of the ascocarp wall; such a fruit-body is termed saucer-shaped organ, thus completely exposing the layer of asci a cleistothecium (cleistocarp). The Erysiphaceae are a sharply which forms the hymenium. Such an ascocarp goes by the name of marked group of forms which live as parasites. They form a super-| apothecium. Owing to the shape of the fruit-body many of these ficial mycelium on the surface of the plant, the hyphae not usually forms are known as cup-fungi, the cup or apothecium often attaining penetrating the tissues but merely sending haustoria into the epi- a large size, sometimes several inches across (fig. 12). Functional dermal cells. Only in rare cases is the mycelium intercellular. male and female organs have been shown to exist in Pyronenia and Owing to their appearance they go by the popular name of mildews. Boudiera; in Lachnea stercorea

VID Sphaerotheca Humuli is the well known hop-mildew, Sphaerotheca both ascogonia and antheridia

ce quilo Mors-Uvae is the gooseberry mildew, the recent advent of which are present, but the antheridium cocina has led to special legislation in Great Britain to prevent its spreading, is non-functional, the ascogonial1

Inga as when rampant it makes the culture of gooseberries impossible. (female) nuclei fusing in pairs; Erysiphe, Uncinula and Phyllactinia are other well-known genera. this is also the case in Humaria The form of the fruit body, the difference and the nature of special granulata and Ascobolus furfure outgrowths upon it--the appendages-are characteristic of the aceus, where the antheridium is various genera. Besides peritheca the members of the Erysiphaceae entirely absent. In H. rutilans, possess conidia borne in simple chains. De Bary brought forward however, both sexual organs are very strong evidence for the origin of the ascocarp in Šphaerotheca absent and

the ascogenous and Erysiphe by a sexual process, but Harper in 1895 was the first hyphae arise apogamously from to prove conclusively, by the observation of the nuclear fusion, that the ordinary hyphae of the mythere was a definite fertilization in Sphaerotheca Humuli by the celim. In all these cases the fusion of a male (antheridial) nucleus with a female, ascogonials Dagen (oogonial) nucleus. Since then Harper has shown that the same Sa listaba

Si no process occurs in Erysiphe and Phyllactinia.

T The Perisporiaceae are saprophytic forms, the two chief genera

Otta

3919 being Aspergillus and Penicillium. The blue-green mould P.

baa lio) boos

Om os crustaceum and the green mould A. herbariorium (=Eurotium

Lead herbariorum) are extraordinarily widely distributed, moulds being found on almost any food-material which is exposed to the air.

anegra FIG. 13.--- Ascobolus furfuraceus. They have characteristic conidiophores bearing numerous conidia,

ambian Diagrammatic section of the frucand also cleistothecia which are spherical in form and yellowish in

Stification. After Janczewski.) colour. The latter arise from the crown of a spirally coiled archicarp

coloniai na (bearing an ascogonium at its end) and a straight antheridium.

m, Mycelium. Vegetative hyphae then grow up and surround these and enclose Buch der Botanik, by permis

4, Archicarp.

bololto 1, Pollinodium.

Goose them in a continuous sheath of plectenchyma (fig. 11). It has lately sion of Gustav Fischer. been shown by Fraser and Chambers that in Eurotium both

Sy Ascogenous filaments. We will FIG. 12.-Peziza aur.

antiaca. (After Kromb- T, P, The sterile tissue from which D holz, nat. size.)

Be the paraphyses k spring. E

ascogonium and antheridium contain numerous nuclei; they are
to be looked upon as gametangia in which there is no differentiation
of gametes, and since they act as single gametes they are termed
coenogametes. In some forms as in Ascobolus the ascogonium is
multicellular, the various cells
communicating by pores in
the transverse walls (fig. 13).

In the Helvellaceae there is
F

no apothecium but a large
'irregular fruit body which at
maturity bears the asci on its
surface. The development is
only slightly known, but there
is some evidence for believing

that the fruit-body is closed in maibibiwa

cits very carly stages. bas

The genus Peziza (in its (219)

csbig widest sense) may be taken as 13) toge

the type of the group. Most togel

16

of them grow on living plants
or on dead vegetable remains,
very often on fallen wood; a

number, however, are found on siinse no tota

growing on earth which is rich Pastel deur babend 4 otas. J:

BMI in humus. The genus Sclero* FIG. 11.-Development of Eurotium repens.. (After De Bary.)

tinia may be mentioned here;

a number of forms have been A, Small portion of mycelium D, The perithecium. with conidiophore (c), and E, F, Sections of young peri- conidia are fragrant and are

investigated by Woronin. The young archicarp (as).

thecia. B, The spiral archicarp (as), w, Parietal cells.

moria carried by bees to the stigma

of the bilberry; here they with the antheridium (p). f. Pseudo-parenchyma. D, The same, beginning to be as, Ascogonium.

germinate with the pollen and 1 surrounded by the hyphae G, An ascus.

From Strasburger's Lehrbuch der Bolanik,

the hyphae pass with the pollen by perinission of Gustav Fischer. forming the perithecium wall. H, An ascospore.

tubes down the style; the
former infect the ovules and spora fimiseda in longitudinal section

FIG. 14.-Perithecium of Podo.

produce sclerotia, therein reascogonium and antheridium contain a number of nuclei (i.e. are ducing the fruits to a mum

After v. Tavel.

000 coenogametes), but that the antheridium disorganizes without mified condition. From the s, Asci. passing its

contents into the ascogonium. There is apparently a sclerotia later the apothecium 4, Paraphyses.imginaldatu nuclei in pairs. Aspergillus Oryzae plays an important part in heteroica, is heteroecious: the m, Mycelial hyphae. Samog saccharifying the starch of rice, maize, &c., by means of the abundant ascospores infecting the leaves of Vaccinium uliginosum, while the diastase it secretes, and, in symbiosis with a yeast which ferments conidia which then arise infect only

Ledum palustre. This is the the sugar formed, has long been used by the Japanese for the pre-only case of heteroecism known in the vegetable kingdom outside paration of the alcoholic liquor saké. The process has now been the Uredineae. successfully introduced into European commerce.

Pyrenomycetes --This is an extraordinarily large and varied group Discomycetes.-Used in its widest sense this includes the of forms which mostly live parasitically or saprophytically on Hysteriaceae, Phacidiaceae, Helvellaceae, &c. The group is I vegetable tissue, but a few are parasitic on insect-larvae. The group

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is characterized by a special type of ascocarp, the perithecium. | This nuclear association of equivalent 'nuclei apparently represents This is typically of a flask-shaped form opening with

a small pore at a reduced sexual process (like the fusion of female nuclei in Humaria the top. The asci live at the bottom often mixed with paraphyses, granulata and of vegetative nuclei in H rutilans, among the Ascowhile the upper "neck" of the flask is lined with special hyphae, mycetes) in which, however, the actual fusion (normally, in a sexual the periphyses, which aid in the ejection of the spores (fig. 14). process, occurring immediately after association) is delayed until The simpler forms bear the perithecia directly on the mycelium, but the formation of the basidium. During the tetrad division in the the more highly developed forms often bear them on a special basidium nuclear reduction occurs. There is thus in all the Basidiales mycelial development--the stroma, which is often of large size and an alternation of generations, obscured, however, by the apogamous speciat shape and colour, and of dense consistence. The cytological transition from the gametophyte to sporophyte. The sporophyte details of development of the perithecia are not well known; most may be considered to begin at the stage of nuclear association and of them appear to develop their ascogenous hyphae in an apogamous end with the nuclear reduction in the basidium. way without any connexion with an ascogonium. Besides the Uredineae. --This is a large group of about 2000 forms. They are special ascocarps, accessory reproductive organs are known in the all intercellular parasites living mostly on the leaves of higher majority of cases in the form of conidia.

plants. Owing to the presence of oily globules of an orange-yellow Tuberineae.-These are a small group of fungi including the well-or rusty-red colour in their hyphae and spores they are termed known truffles. They are found living sa prophytically (in partRust-Fungi. They are distinguished from the other fungi and the parasitically) underground in forests. The asci are developed in rest of the Basidiales by the great variety of the spores and the the large dense fruit bodies (cleistothecia) and the spores escape by great elaboration of the life-history to be found in many cases. the decay of the wall. The fruit-body is of complicated structure, Five different kinds of spores may be present-teleutospores, but its early stages of development are not known. Many of the sporidia (= basidiospores), aecidiospores, spermatia and uredospores fruit-bodies have a pleasant flavour and are eaten under the name of (fig. 16). The teleutospore, with the sporidia which arise from it, truffles (Tuber brumale and other species). The exact life-history is always present, and the division into genera is based chiefly on of the truffle is not known.

Laboulbeniinese are a group of about 150 species of fungi found to be a such on insects, especially beetles, and principally known from the re

Onod sada stwo

sp

articinal searches of Thaxter in America. The plant is a small, dark brown,

B

20:00 erect structure (receptacle) of a few cells, and 1-10 mm. high, attached

sp to the insect by the lowermost end (foot), and easily mistaken for a hair or similar appendage of the insect. The receptacle ends above in appendages, each consisting of one or a few cells, some of which are the male organs, others the female organs, and others again may

Ti 03

be be barren hairs. The male organ (antheridium) consists

of a few second cells, the terminal one of which either abstricts from its end, or emits resolby um from its interior the non-motile spermatia, reminding us of those around of the Florideae. The female organ is essentially a flask-shaped TOPURTON 6

tud structure; the neck of the flask growing out as the trichogyne, and the belly composed of an axial carpogenic cell surrounded by investing cells, and with one cell (trichophoric) between it and the tricho

Pokud gyne. These three elements-trichogyne, trichophoric cell, and carpogenic cell-are regarded as the procarp. The spermatia have been shown by Thaxter to fuse with the trichogyne, after which the axial cell below (carpogenic cell) undergoes divisions, and ultimately forms asci containing ascospores, while cells investing this form a perithecium, the whole structure reminding us essentially of the fructification of a Pyrenomycete. Many modifications in details

occur, and the plants may be
dioecious. No injury is done to
the infested insects. It has lately
been shown that there is a fusion
of nuclei in connexion with ascus
formation, so that there can be
no doubt of the position of this
extraordinary group of plants
among the Ascomycetes. The
various cells of these organisms

S.
are connected by large pits

FIG. 16.-Puccinia graminis.
which are traversed by thick
B

protoplasmic threads connecting A, Mass of teleutospores (1) on a vulgaris, with a, aecidium
one cell with the next. In this leaf of couch-grass.

fruits, P, peridium, and sp. point and in their method of Epidermis ruptured.

spermogonia. (After Sachs.) fertilization the Laboulbeniineae 6, Sub-epidermal fibres. (After C, Mass of uredospores (ur). suggest a possible relationship

De Bary.)

with one teleutospore (l): of Ascomycetes and the Red B, Part of vertical section sk, Sub-hymenial hyphae. (After From Strasburger's Lehrbuch der Botanik,

through leaf of Berberis Algae. by permission of Gustav Fischer,

De Bary.) FIG. 15.-Armillaria mellea. (After

Basidiales.-This very large

group of plants is characterized its characters. The teleutospore puts forth on germination a fourA, Young basidium with the two by the possession of a special celled structure, the promycelium or basidium, and this bears later B, After fusion of the two nuclei. idium, which gives its name to infect a plant the

mycelium so produced gives origin to aecidiospores Hypholoma appendiculatum.

The basidium is and spermatia; the aecidiospores on infection produce a mycelium C. A basidium before the four a unicellular or multicellular which bears uredospores and later teleutospores. This is the lifenucleiderived from the second

structure from which four bas- history of the most complicated forms, of the so-called cu forms. ary nucleus of the basidium idiospores arise as outgrowths; In the opsis forms the uredospores are absent, the mycelium from the

have passed into the four but soon, like the ascus, becomes hemi the aecidiospores are absent, the mycelium from the sporidia D, Passage of a nucleus through uninucleate by the fusion of the giving origin directly to the uredospores; the former possess sper

the sterigma into the basidio two nuclei. Then two successive mația, in the latter they are absent. In lepto and micro forms both spore.

nuclear divisions occur resulting accidiospores and uredospores are absent, the sporidia producing a

in the formation of four nuclei mycelium which gives rise directly to teleutospores; in the lepto which later migrate respectively into

the four basidiospores (fig. 15), forms the teleutospores can germinate directly, in the micro forms The Basidiales are further characterized by the complete loss of only after a period of rest. We have thus a series showing a progres. normal sexuality, but at some time or other in the life-history sive reduction in the complexity of the life-history, the lepto and there takes place an association of two nuclei in a cell; the two micro forms having a life-history like that of the Basidiomycetes. nuclei are derived from separate cells or possibly in some cases are The eu and opsis forms may exhibit the remarkable phenomenon sister nuclei of the same cell. The two nuclei when once associated of heteroecism, i.e. the dependence of the fungus on two distinct are termed "conjugate" nuclei, and they always divide at the same host-plants for the completion of the life-history. Heteroecism time, a half of each passing into each cell

. This conjugate

condition is very common in this group and is now known in over one hundred is finally brought to a close by the nuclear fusion in the basidium. and fifty species. In all cases of heteroecism the sporidia infect Between the nuclear association and the nuclear fusion in the one host leading to the production of accidiospores and spermatia basidium many thousands of cell generations may be intercalated. (if present), while the aecidiospores are only able to infect another

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