13i FISH HATCHING, 



I have already stated that the young fish 

 are nourished by tlie gradual absorption of 

 the contents of their umbilical vesicle, but 

 there is, I believe, a phenomenon about this 

 which has not hitherto been observed, or, if 

 observed, not carefully examined. I have 

 noticed, and so has Mr. Ponder, that in many 

 of the young fish the umbilical vesicle has 

 two coats or coverings, so that as the con- 

 tents of the internal coat are absorbed, the 

 external coat is seen, (especially at the lower 

 extremity,) hanging loose and empty, so that 

 one sees plainly a bag suspended within 

 a bag. 



Again, in the young fish we may clearly 

 perceive the remarkable action of the two 



surface on to wliicli tlie figures were thrown, to the delight of 

 those present, and the great discomfort of the fish themselves. 



