THE SPAWNING AND DEVELOPMENT OF THE COD-FISH. 219 



young fish has meanwhile grown so niuch, that its body already shows 

 a complete circular bend following the outlines of the egg, so that the 

 tail-end, which is now surrounded by a membrane clearly perceived, 

 (the embryonal fin,) reaches to the mouth, and later, even somewhat 

 beyond it. 



At the end of the sixteenth day, the young fish is ready to slip out of 

 the egg. Its movemeuts inside the egg have now become so powerful, 

 that it frequently assumes an entirely different position from that which 

 it had at first. The iris is completely colored and even shows traces of 

 that peculiar silvery gloss which is so prominent in the more developed 

 fish. It has a deep incision in its lower rim which only gradually dis- 

 appears. The pigment of the body is diffused in such a maimer that it 

 appears in larger quantities at the root of the breast-fins and along the 

 upper side of the entrails ; also on the back part of the body, where it 

 forms two dark ribbons, consisting of numerous star-shaped dots, which 

 remain unchanged long after the fish has left the egg. At last the skin of 

 theegg bursts, and the young fish slowly frees itself from the remnants still 

 clinging to it. At first the body has still the bent shape which it had while 

 inclosed in the egg, but finally it straightens, and the young fish moves 

 about with its special tremulous motions. It has now that peculiar un- 

 developed appearance so characteristic of all young fish, and so different 

 from that of the adult. This peculiar appearance is chiefly produced by 

 the large yelk-bag still clinging to it, and which is arranged so as to fur- 

 nish its only supply of food, till the mouth has opened and the intestinal 

 channels have formed themselves into a closed tube, connecting with 

 the mouth. The body is very thin and tender, and with the exception 

 of the above-mentioned pigment gatherings, almost entirely colorless, 

 showing distinctly in the middle the chorda dorsalis, and on both sides 

 of this the regularly-arranged muscles of the body. The front part of 

 the body still shows a faint downward bend, a reminiscence of the foetal 

 curve; the head projects sharply from the rest of the body, looks as if 

 it were swollen, and has a round shape, the mouth, or rather the region 

 of the forehead, projecting a little. On the upper side of the yelk bag 

 can be seen the intestinal channel. It is still almost entirely straightl 

 and terminates at about one-third part of the body, or in that place 

 where the back part of the yelk-bag is closed. At its foremost end, 

 which is bent somewhat to the right, a round finegrained mass is seen, 

 which is the liver; and immediately above this are, on each side, the 

 round breast-fins, turned upward, anil transparent as clear water. The 

 body is surrounded by a transparent membrane, which begins immedi- 

 ately above the mouth and stretches round the whole body as far as the 

 yelk-bag. Its foremost part is widened out to a sort of cap, while toward 

 the tail it is strongly compressed ; and while the auimal is in motion 

 this takes the place of those tins which are still wanting. The yelk-bag 

 now begins gradually to collapse, and at the same time begins the forma- 

 tion of the mouth by the lower jaw, which formerly was firmly joined to 



