220 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



the upper one, becoming gradually detached from it. When the yelk- 

 bag has become completely absorbed, which takes place about two weeks 

 after the slipping out of the young fish, the mouth is already distinctly 

 developed, but as yet of a shape very different from that of the grown 

 fish, as the lower jaw, as in the case of those deformed fishes called 

 " cod-fish kings," projects considerably beyond the upper one, which 

 rises quite straight. The young fish now already shows its peculiar 

 gulping movements, and eagerly snaps after microscopical animals and 

 algae. It is no longer so much exposed to the currents and the winds as 

 formerly, when the yelk-bag kept it up on the surface of the water, but 

 often makes short excursions to a considerable depth, in order to hunt 

 small animals, with which the sea at this time is swarming. The changes 

 that follow are chiefly in the inner organs ; thus the bile develops itself 

 distinctly; the blood, which at first was entirely colorless, assumes a 

 faint yellowish tinge, and can be seen circulating through the body in 

 regular courses; the intestinal channel has increased in length, and in or- 

 der to find room, must describe one or several convolutions; the shoulder 

 girdle is already distinctly developed, &c. In the most advanced stages 

 of development which I observed, and which took place in the beginning 

 of May, the body was less transparent, and showed, especially on the 

 head, a distinct yellow color. The distribution of the pigment was also 

 somewhat uneven, being most distinctly visible on the upper side of the 

 head and along the back and the belly. The intestinal channel, in which 

 a wider fore part, (the stomach,) and a thinner loop-shaped and bent 

 hind part, (the entrails,) could already be distinguished, showed yellow- 

 ish contents, changing into green in the hind part. In the region of the 

 heart, the blood had already a distinct red color. Near the hind part of 

 the body, on the lower side, some fine rays showed themselves in the 

 embryonal membrane, as the first sign of the tail-fin beginning to form 

 under the extremity of the chorda dorsalis. 



My observations on the development of the cod-fish extend no further 

 than this; but I hope next year to be able to continue them through all 

 those interesting changes through which the young fish passes before it 

 becomes fully mature. 



I must remark, in conclusion, that the above- mentioued peculiarity 

 in the roe of the cod-fish, viz, that it develops swimming free in the sea, 

 occurs also in the roe of other fish. During my last stay on the Lofo- 

 ten Islands, I caught, also, with the aid of a fine net, the roe of three 

 other different kinds of fish, entirely unknown to me, aud floating in the 

 sea in exactly the same manner. I am convinced, too, that this is also 

 the case with the roe of the haddock, (Gadus wglefinus,) which spawns 

 about the same time as the cod-fish. On the whole, this may indeed be 

 the case with a much larger number of salt-water fish than is generally 

 supposed. I consider ic, in all probability, applicable to the whole large 

 cod-fish family, and on closer investigation it may be found to extend 

 even much further than this. 



