EMBRYO SALMON DESCRIBED. 221 



one day old. Its length is the seven-eighths of an 

 inch. It is altogether imperfectly formed. Still 

 we see something like mouth, eyes, and head. 

 We see a fringed body, and we see a little sac 

 depending from the region of the thorax. This 

 little bag contains vitelline matter for the sus- 

 tentation of the fish, until it can provide for 

 itself. 



In reference to the above figures, Mr. Young 

 has written: "When the young fish are formed, 

 and while they are confined within the shell of 

 the egg they lie in a circular form, and the burst- 

 ing of this shell is from their endeavours to get 

 straight. The first opening of the shell invari- 

 ably takes place opposite to the back fin, or mid- 

 dle of the fish, and, as it were by the unstringing 

 of a bow, the tail starts out first, and thereby 

 leaves the fish in a straight position. The head 

 of the fish and the conical bag remain in the shell 

 a little longer ; but from the motion of the water 

 and the fish, they very soon throw oflf the last 

 encumbrance, and appear at large in the water. 

 From the first moments of their existence, we find 

 them formed with fear of their enemies; for, 

 from the least shadow passing over them, we find 

 them endeavouring to get shelter underneath the 

 stones and gravel of the pool, to which they hurry 



