PAPERS READ.

MICROSCOPICAL COLLECTIONS IN FLORIDA. By C. C. MERRIMAN, of Rochester, N. Y.

Ir has been my fortune during the past two winters to spend a few weeks in the regions of central Florida. Lake Harris is the most southern and the most beautiful of the cluster of lakes which forms the source of that exceedingly picturesque river, the Oklawaha. With high banks and surrounded by a belt of hummock land, as rich as any that Florida affords, this lake is becoming settled upon, and the lands are fast being taken up by enterprising southerners for orange groves and pine-apple plantations. The sojourner will find the society of this lake settlement intelligent and hospitable beyond anything that would be suspected in so new and pioneer a country. The vegetation of this almost tropical region is so full of interest to the microscopist, and the causes conducing thereto so peculiar, that I have thought them deserving of especial mention and illustration.

The absence, or at least the rarity of frosts, injurious to vegetation in these lake districts, gives the longest possible season for the growth and maturity of such organs as are best or especially adapted to the exigencies of Florida plants. There is a period of rest, usually comprising about the three winter months, after which vegetation takes up and continues its growth again as if there had been no period of interruption; so that practically there is a continuous development of plant life, whether annual or perennial, from birth to death.

The soil of Florida, as of all the south Atlantic seaboard, is sandy and naturally barren. No polar glaciers have ground up for these regions, as for the northern states, a rich and abundant alluvium, sufficient in itself for the production of a rapid and vigorous vegetation. The south has apparently only the siftings of our northern soil, carried down to the ocean by rivers, and then washed up by the sea-waves to form their interminable sandy plains. But to compensate for this natural infertility of soil the atmosphere, especially of southern Florida, abounds in all the

elements of plant growth. The winds which come up from the Gulf on the one side, or the Atlantic on the other, are charged with moisture, and bear also minute quantities of nitric acid and saline compounds; while the exhalations from the swamps and marshes furnish in abundance the salts of ammonia and carbonic acid. Now to utilize these precious products from the air it is necessary for plants to have peculiar organs, such as absorbing glands, glandular hairs, stellate hairs, protecting scales, and a variety of other special appendages. All these have been developed by time and necessity in remarkable profusion and perfection on the vegetation of southern Florida. Although the meagre soil produces no nutritious grasses, and scarcely enough of an honest vegetation to keep an herbivorous animal from starving, yet there is an abundant flora, such as it is-air plants, parasitic growths, insectivorous plants, and strange herbs seeking a livelihood in any other way than the good old honest one of growing from their roots. It is this fact which makes the microscopical interest of botanical researches in central Florida. One can scarcely examine, with a two-thirds objective, the flowers, leaves or stems of any plant growing there, without discovering some beautiful or striking modification of plant hairs, or scales, or glands, or other absorbing or secreting organs.

We will notice first the Onosmodium as found in Florida — 0. Virginianum. It grows from Virginia south, but is more glandular, I think, in Florida than anywhere else. It will be almost the first plant one will stop to observe on entering the piny woodsa dark green, narrow-leaved, biennial herb; its straight stem of the second year's growth, about a foot high, bearing a raceme-like cluster of flowers, coiled at the end, and straightening out as the flowers expand. The leaves of this plant are thickly studded on both sides with stiff transparent hairs, lying nearly flat on the surface, and all pointing towards the tip end of the leaf. At the base of each hair is a cluster of glandular cells, amounting sometimes to fifty or more, and arranged in beautiful geometrical forms. When pressed and dried in the herbarium, the body of the leaf turns to a very dark green, almost black, and on this background, with a half-inch objective, the hairs stand out like sculptured glass, and the glands like mosaics of purest pearls. I think it is the most attractive opaque object that can be shown under the microscope.

That these glandular cells, covering, as they do, nearly half the surface of the leaves, especially the upper surface, and differing from all other vegetable cells, subserve an important purpose in the sustenance of the plant, there cannot be any doubt. But just what that purpose is, or what is the mode of operation, I think," has never been ascertained.

In the same locality will very likely be found the most beautiful of all the Croton plants, the C. argyranthemum. Unlike the other Crotons, which are bushes, this is an herb growing only about a foot high, with a milky sap which exudes when the stem is broken. The leaves are silvery, verging in some cases to a bronze color, and are thickly covered on the upper side with most remarkable and beautiful stellate scales. The flower buds and stems when pressed make much more beautiful opaque objects than the leaves.

The object of these scales is without doubt to prevent the too rapid evaporation of the moisture stored up in the plant. They are the exquisitely woven blankets which preserve the precious juices so laboriously gathered. The same kind of covering is spread over the leaves and stems of all the air-plants of Florida, and doubtless for the same purpose. The well-known Florida moss, although not a moss, but a member of the Pineapple family (Tillandsia usneoides), is an exceedingly beautiful object under the microscope. Each hanging stem is overlaid with filmy white scales, every one of which is fastened in its place by what would seem to be the stamp of some miniature seal on golden-tinted This plant, as ordinarily seen on the live-oaks near cities, is a dirty-looking and unattractive object, and goes by the name of "black moss." But in out-of-the-way places, removed from the dust and smoke of settled localities, it is pearly white and exceedingly beautiful, both to the naked eye and under any power of magnification. Florida moss should be preserved with only very slight pressure, just enough to make the threads lie straight. After it is dried in this way, small cuttings may be mounted in the ordinary cells for opaque mounting.

wax.

On the high banks of the lake, and in the adjoining fields, may be found the large leaved and vigorous growing Calicarpa (C. Americana), sometimes called the French mulberry, a bush growing some five or six feet in height. The under side of the leaves of this plant is nearly covered with little round yellow sessile glands, flattened on top and marked off into eight or ten sections

by ribs, like those on a melon. They are in immense numberssomething like thirty thousand to the square inch- -over half a million on a good sized leaf. Under a light net-work of branching glandular hairs, viewed with a two-thirds objective, these polished amber-colored disks glisten like a spangle of golden beads. The same kind of glands are found on the leaves of many other shrubs in Florida-the sweet myrtle (Myrica cerifera), the low ground blueberry (Vaccinium tenellum), a certain bush or dwarf hickory (Carya glabra), and some others. These glands have been variously called resin dots, resin glands, and odoriferous glands. So far as I can judge, however, they are not connected with any resinous or odoriferous secretions. From their almost perfect resemblance to the terminal bulb of the mushroom glands of the Pinguicula and Drosera, which are known to be absorbing glands, the probability is that these also serve to absorb moisture and ammonia from the atmosphere and from rains; although I am free to acknowledge that the position of the glands, being for the most part on the under side of the leaves, militates somewhat against this view of their purpose.

Great care will have to be taken in pressing and drying vegetable specimens in the moist climate of Florida. The little threads of the mould fungus will be sure to creep over the surface of the leaves, spoiling them for microscopical material, if they are not quickly and effectually dried. For this purpose it is well to have a good supply of the bibulous botanical paper, and to change the specimens every day to fresh sheets for at least four or five days. The sheets after being once used should be spread out in the sun to dry. A weight of about thirty pounds may be used as the pressure.

The objects heretofore mentioned are all for opaque mounting. Almost every preparer of slides has his own favorite method for this kind of work. I myself prefer the use of the transparent shell-lac cells. Clarified shell-lac is dissolved in alcohol, and filtered through cotton wool under a bell-glass and with the appliIcation of heat. The solution is evaporated down until it is so thick that it will only just run, almost like a jelly. In this condition it can be put on a slide with a camel's-hair brush on the turntable, and very quickly worked up into a ring with the point of a knife, used first on the inside to make the cell of the size wanted, and then on the outside to turn the cement up into a compact ring.

Two or three applications of the cement, with intervals of a day or two after each, will make cells of sufficient depth for all ordinary specimens. These cells dry quite slowly, and if artificial heat is used, it must be increased only very gradually, otherwise vapor of alcohol bubbles will make their appearance in them. A small ring of Brunswick black may be made in the inside of the cell, to which, when thoroughly dry, the object may be fastened with a very little liquid marine glue. In this case both sides of the leaf can be seen, which is often desirable. In all opaque mountings a minute aperture should in some way be left open into the inside of the cell, so that it shall not be hermetically sealed up. This little precaution will save an innumerable number of failures.

The collector in Florida will not fail to secure a supply of the leaf stems of the castor-oil plant (Ricinus communis). In regions beyond the influence of frosts this plant grows continuously from year to year, and becomes quite a tree. It is only in such a growth that the spiral tissue of the fibro-vascular bundles is fully perfected. The castor-oil plants grown in our climate, during one short season, will furnish very little spiral tissue, mostly spotted ducts, and scalariform cells. There is no more beautiful object for multiple staining than thin longitudinal sections through the woody fibre, the vascular tissues, and the pith cells of well matured leaf stems of the castor-oil plant.

I will briefly describe my process of making these stainings. After being decolorized in chlorinated soda, the sections may be left for half a day or more in a solution of carmine in water containing a few drops of aqua ammonia; then for half an hour in a rather weak solution of extract of logwood in alum water, and finally ten to fifteen minutes in a weak solution of aniline violet or blue in alcohol. From this they can be carried through absolute alcohol into turpentine, and mounted in balsam at any time thereafter. If successful in this staining you will have the pith cells in red, the spiral tissue in blue, the wood cells in purple, and the stellate crystals in green or yellow.

But the chief objects of interest to the microscopist in the vegetation of Florida are the insectivorous plants. Not only are they more abundant, and as I think more perfectly developed in the central lake regions of Florida, but some varieties are found there differing, it seems to me, from any found elsewhere. I desire particularly to mention one which I discovered, and which