I have not the least doubt, from the appearance of the fish, but what all the deaths that occurred before the 15th were from bruises occasioned by the shingle, as, besides the congested appearance mentioned, one of the turbot had the lower opercle torn and the gill injured. I would not use any substance for them to bed in, notwithstanding they love to bury themselves. I think that there is little danger of a sole being injured by friction on the bottom, for they can stick fast there or on the sides at pleasure. I have even seen them in the aquarium holding to the glass. Do not remember seeing turbot do this, but think that possibly they can hold to the bottom as other flat fish do. I noticed that neither of these fish have ribs protecting the abdominal cavity, which is particularly exposed to injury. The majority of them dying on the morning of the 11th, between the change of water at 4, and my arrival at 8, at once shows something wrong in the water. The two soles that were in the can with the turbot were well on the fatal morning, and might not have had a change; the men were contradictory on this point; were put with the others that survived, making six, all of which died except two, but their identity was lost, and I cannot say if they were the survivors.

However, the fact of getting two across safely proves that soles, and perhaps turbot, can be brought over under more favorable circumstances, though I cannot conceive of a better ship than the Siberia for fish transportation, and Captain McKay considers the Parthia as good. I regard the season as not only bad for transportation, but also for planting, as the fish being turned loose in midwinter had no chance to gradually work into warmer water, which is at greater distance from Boston than any part of England, and the sole swims slowly and apparently laboriously. I have only seen them in aquaria where they are usually on the bottom and occasionally start with a leech-like motion for a short distance and settle down again, not seeming to possess the power of elevating their heads and darting as the flounder does. On the arrival of the tugboat I received a letter of introduction to Mr. C. B. Simmons, collector of customs for the port of Boston, who had so kindly offered to Professor Baird the use of the revenue-cutter to deposit the fish, should they arrive; this I, of course, did not use. The letter of instructions, also received at the same time, directed the fish to be planted "at some point off Nahant," and it is worthy of note that this locality was selected some two hours before getting the letter. I would much prefer soles that had been fed in captivity a month, to any recently captured, if the attempt was again made.

XVIII. HOW CAN THE CULTIVATION OF THE OYSTER, ESPECIALLY ON THE GERMAN COASTS, BE MADE PERMANENTLY PROFITABLE?*

By Dr. KARL MÖBIUS.

The first condition of successful oyster cultivation on our coasts is a knowledge of the character of our natural oyster-beds. The majority and the best of them are near the islands of Sylt, Amrum, and Föhr. At the northern boundary of our oyster territory, near the island of Röm, and at its southern boundary, near the islands of Pellworn and Nordstrand, not far from the city of Husum, there are but few and small beds. Farther south, near the mouths of the Eider and the Eibe, there are none.

As the oyster-beds share the character of that portion of the sea in which they are located, it is necessary to cast a glance at the character of the Schleswig-Holstein Archipelago.

Compared with the open German Ocean it is a shallow sea. In the whole southern portion of the open German Ocean between Germany, Holland, and England the average depth varies from 35 to 45 meters. In the Schleswig-Holstein Archipelago no such depth is found. The greatest depth of the channels by which it is connected with the open sea averages 15 to 20 meters. The bottom of the archipelago, therefore, rises like a plateau above the deeper ground of the German Ocean. The plateau is intersected by valleys of varying depth and breadth. When the tide is in, the plateau is entirely covered with water, but when the tide is out, large spaces are dry; and these are called "Watten," from which this whole sea is also called the "Watten Sea."

When the tide goes out, the water flows through these valleys (called "deeps" by the sailors) both in a northerly and a southerly direction into the open German Ocean, until the tide when it comes in, which occurs twice a day from two sides, makes the water flow back. It rises and the valleys can no longer contain the water. It overflows the banks and inundates the "Watten" to such an extent that small vessels can sail over the same place where a few hours ago men could walk and drive wagons. For at high tide the water in the "Watten Sea" stands 6 feet higher in the north and 9 feet higher in the south than when the tide is low. The current of the water is therefore in

* Address made at the meeting of the German Fishery Association at Berlin, March 16, 1876, by Dr. Karl Möbius, of Kiel. [From Circular No. 3 of the Deutsche FischereiVerein, Berlin, March 21, 1877.] Translated by Herman Jacobson.

many places as rapid as the Rhine near Bonn, its rapidity being 1 to 2 meters a second.

The bottom of this turbulent ocean is mainly composed of quartz-sand. Farther away from the strong currents the so-called "schlick” is deposited a clayey mud containing organic matter; this is the case at many points of the eastern coast of Sylt and on the coast of the mainland. On the slopes between the "Watten" and the deep channels the bottom is for great distances covered with coarse gravel, small and large stones, and shells. In such places we find, besides many other marine animals, colonies of oysters, so-called oyster-beds. As the water is full of little floating particles of clayey mud, these oyster-beds cannot be seen; their location, however, has been known to the fishers for centuries; and they find them by steering their vessels toward high points of the coast and of the islands. The oysters are caught with drag-nets, consisting of an iron frame from which depends a bag composed of iron rings and coarse yarn, with an opening measuring about 1 meter. The whole net weighs about 60 pounds. It is generally drawn along for 5 to 7 minutes; then two or three men draw it up and throw its contents on the deck of the vessel. This consists of old oyster-shells, different animals and plants, and live oysters, which are picked out, freed from all animal or vegetable matter adhering to the shells, and then shipped to the markets.

In no part of the "Watten Sea" do the oysters lie on rocky bottom. The best bottom for them is that which is composed of old oyster-shells. It is an erroneous idea that the oysters stick to the bottom of the sea, or that they lie close together or in layers. In good Schleswig-Holstein oyster-beds the net has to be drawn over a space of 1 to 3 meters square and even larger in order to get a single full-sized oyster.

The number of our oyster-beds is 47, and their extent varies very much. The largest extends one-half German mile (about 24 English miles) in length. Most of them, however, are not so long, and only a few hundred feet broad. Although all the beds are located within a territory 10 German miles long and 3 German miles broad, the quality of the oysters varies very much. If all the 47 beds were put together, they would not cover the hundredth part of that portion of the "Watten Sea" which always remains under water. What is the cause of this? Is there a lack of young oysters to occupy all the vacant spaces between the beds? I cannot suppose that this is the case, and my reasons are the following:

The total number of full-grown oysters in our beds may be about 5,000,000. According to investigations made by me in 1869, at least 44 per cent. of all the full-grown oysters produce young ones; and as every fall-grown, pregnant oyster produces at least 1,000,000 young ones, the number of young oysters produced during the breeding season, which generally lasts from June till August, would be 2,200,000,000,000, sufficient to make the whole "Watten Sea" one continuous oyster-bed;

for if this number of oysters is spread over a space 30 German miles square, there would be 1,332 to every square meter.*

If, in spite of this, the oyster-beds have not extended over the whole "Watten Sea," the reason cannot be that the quality of the water is less favorable to the oyster in some places than in others; for throughout this whole sea it has the same quantity of salt, viz, 3 to 3.2 per cent. The temperature is likewise the same everywhere, for both in the oyster-beds and in other places it varies in the course of the year 200 above to 2o below zero (Celsius). Want of food cannot be the cause why the oysterbeds have for centuries kept within certain limits, for the water of this sea is full of microscopic plants and animals and decaying organic matter, all of which might serve as food for the oysters. The only remaining natural cause which could hinder the oyster-beds from extending and increasing is the unfavorable character of the bottom in the greater portion of the "Watten Sea." Oysters do not flourish on bottom consisting of quicksand or deposits of clayey mud mixed with organic matter. And one of the two is found in the greater portion of the bottom of the "Watten Sea." The size and number of those places where, in spite of the tide, the bottom remains firm and free from deposits, is very limited, and only in these limited spaces oyster-beds can be formed. In order to explain this I must say a few words on the structure and development of the oyster.

The mother-oyster does not lay her eggs immediately in the water, but keeps them in the so-called beard (the gills of the oyster) until the little creatures are able to swim. These young oysters, of a bluish color and 0.15 to 0.18mm long, swarm about in the water and finally settle on the bottom.

If this young oyster gets to a place where there are clean stones or shells on which it can grow, there is a prospect of its reaching its full size, but if it gets on quicksands or muddy deposits, it is lost; for, as it has no feet, like some other shell-fish, it cannot work itself out of the sand and clay.

Most of these young oysters doubtless die very soon, because they find no clean places on which to grow. This circumstance has led to the artificial cultivation of the oyster in France, whose author is Professor Coste, of Paris. In the spring of 1858 he distributed in the bay of St. Brieux shells and heavy fagots over a space of 1,000 hectares (1 hectare = 2.4711 acres), and on these spread 3,000,000 mother-oysters. In autumn all the fagots were of course covered with young oysters; for, if these oysters were as fruitful as the Holstein oysters, there were 132,000 young oysters to every square meter. The boldest expectations were exceeded. It was thought that now the means had been found to surround every French coast with oyster-beds, and people already com

* In a work on "The Oyster and its Cultivation," which I intend to publish very soon, I shall give the data on which these figures are based. I feel convinced that they are not exaggerated, but are rather below the actual figures.