428 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. [2] 



tbin sliell, and do not contain drops of fat. The shell of tbe egg, under 

 a .powerful magnifying glass, has the appearance of fine wavy fibers, 

 crossing each other irregularly. There are, however, no real fibers, but 

 they are simply thicker portions of the egg shell. These thick places 

 vary greatly in different eggs ; in some they are not found at all, but in 

 that case the porous channels appear very distinctly as numerous deli- 

 cate dots. In my opinion, this fibrous appearance is caused by a 

 shrinking of the contents of the egg, which gives less tension to the egg 

 shell, but does not hinder the development of the egg. The mature 

 eggs are not sticky. The eggs of the plaice are large, and those of the 

 flounder small; but the smallest of all (less than one millimeter) are those 

 of the Platessa Umanda. I have not been able to observe any difference 

 between the eggs of the cod and of the plaice, excepting in the outer 

 structure of the shell, unless it be that in the egg of the plaice there is 

 by the side of the micropyle a dot, almost resembling a second micro- 

 pyle, which I did not see in the eggs of the cod. Impregnated eggs, 

 which have not yet developed, can only be distinguished from other 

 eggs, with the naked eye, by the circumstance that the yolk of the cod 

 egg is decidedly yellowish, whilst in the plaice egg it is colorless. 



When I received the first specimens of mature female plaice their de- 

 veloped eggs, when placed in water, sank to the bottom. Judging from 

 this observation it seemed possible that the eggs were piled up in holes 

 in the bottom or laid in nests, or that the fish simply scattered their 

 eggs on the bottom. The first question, therefore, was to find the place 

 where the fish deposited their spawn. I was informed that in March 

 (the spawning season of the plaice and flounder being in March and 

 April, and that of Platessa Umanda in May) plaice had occasionally 

 been found lying close to the side of each other on the coast near Fried- 

 richsort (bay of Kiel), just as if they had gathered in certain places 

 for the purpose of spawning. 



Young plaice are, in autumn, found in great numbers among the sea- 

 weed, and in shallow i)laces near the coast. I have found them partic- 

 ularly near Eckrenforde; but similar reports have also reached me from 

 Flensburg and from Stein on the bay of Kiel. In summer Professor 

 Mobius has also caught young fish floating about freely in the inner 

 bay of Kiel ; but we have not yet succeeded in catching very young 

 fish. Therefore, it seemed proper to commence the investigation by 

 endeavoring to obtain some of these fish. 



For a number of years but very few plaice have been caught in the 

 inner part of the bay of Kiel. Only in 1882, when the saltness of the 

 water was unusually marked, and when a number of marine animals 

 from the North Sea — otherwise not found in these waters — had made their 

 appearance, and then but temporarily, did the plaice fisheries flourish in 

 the inner bay. For this reason the attempt to catch young fish had to 

 be made near the mouth of the bay. I could not take part in these ex- 

 periments, and the fishermen whom I had engaged for the purx)ose only 



