132 THE CANADIAN NATURALIST. [Aprils. 



ter, — but tlie fish inside the egg most certainly increases in bulk^ 

 till at last it becomes so large that the egg-shell suddenly bursts^ 

 and out comes the young fish. 



In the gradual development of the young salmon and trout we? 

 begin with a globule of albumen. We see within it a faint line, and 

 two black spots. Day by day these become larger, till the young 

 fish is born. After this, the umbilical vesicle is absorbed, the 

 color appears on the scales, the long single crests, which one ob- 

 serves at birth running down the upper and lower parts of the 

 body, resolve themselves, as it were by magic, into the various fins 

 distinctive of the adult creature, and we have a perfect fish 

 before us. 



It is most interesting to watch an egg at the moment of hatch- 

 ing. You may happen to be gazing on a particular egg, when of 

 a sudden you will see it split in twain, at the part corresponding 

 with the back of the fish; you will then see a tiny head with 

 black eyes and a long tail appear, and you will see the new-born 

 creature give several convulsive shudders in his attempts to free 

 himself from the now useless shell. Poor little fellow ! he can't 

 manage to get out : the shell is too tight for him. Take, there- 

 fore, a soft hair-pencil, press lightly on the egg-shell, — he seems to 

 know you are his friend, — he gives another vigorous kick or two 

 and presto ! he is free, and has commenced life. If we judge 

 from his motions, he must enjoy it, for away he swims as fast as 

 his tiny and wriggling tail will carry him, round and round in 

 a circle, and then plump down he goes to the bottom of the tank, 

 and reclines on his side, breathing freely with his gills for the 

 first time in his life. 



It would appear that it is not possible for the fish to remain 

 long enough in the egg to come out ready to eat food at once, as 

 is the case with the ovo-vivipaious creatures. They have therefore 

 attached to their belly a bag, which contains the nourishment that 

 the young fish must absorb before they are able to shift for them- 

 selves. The moment the contents of the bag are gone, they begin 

 to feed with the mouth. 



In various creatures the progress of development is different. 

 Thus, for instance, in the human baby, the first portion of the body 

 developed is the lower jaw, and this for an obvious reason, because 

 the most material want of the baby is to obtain the mother's milk 

 by suction. 



