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but am not sure of the circumstance. There is, however, 

 another point in connection with this of great interest. It 

 appears as the fish grows, that this caudal extremity of the 

 vertebra is entirely absorbed, and instead of it we find a 

 number of cartilaginous strioc, which extend equally on 

 each side of the vertebra, and form the caudal fin of the 

 fish — and while this is going on, the dorsal fins are likewise 

 being strengthened by additions of cartilage disposed in striae. 

 As I have explained, that during the growth of the young 

 fish the umbilical vesicle is gradually absorbed, and that 

 during that time various other changes are taking place in 

 other parts of the animal, such as the formation of cartilage 

 and skin and bone — it appears to me a point of peculiar in- 

 terest to determine, how the contents of the vesicle aid in 

 this change. Now, physiologists tell us that aU parts of the 

 frame are built up by the blood, and that this blood is re- 

 newed by the absorption of the nutritious elements con- 

 tained in the food we eat ; no matter what that food is, it 

 is all converted into flesh and bone by the wonderful elabo- 

 ration of nature. It appears, also, that the liver plays an 

 important part in the chemical changes produced on the 

 food. May not this liver in the fish, taking up, as it ap- 

 pears to do, the venous blood returning by the great dorsal 

 vein, aid in preparing the contents of the umbilical vesicle 

 for assimilating in the body ? This is merely my sur- 

 mise, which I offer witti some difiidence. The contents, 

 again, of this vessel are, I believe, albumen and oil globules. 

 At any rate, the former fluid coagulates with alcohol, and 

 the latter float on the water when the contents of the 

 cist are burst. Again, the colouring matter of the 

 oil appears gradually in the fins and vertibra of the fish, 

 as I have frequently observed. In conclusion, let us con- 

 sider the obvious reason why the young salmon should be 

 burn in so incomplete a state with this umbilical appendage. 

 The parent fish deposits her eggs in the gravel of running 

 water, where they are exposed to numerous enemies, and 

 consequently where, if hatched quickly, they will better 

 have an opportunity of escape. The ova arc about 90 days 

 hatching, but are not perfected under 140 days, during 



