MALFORMATION OF FISH FRY. 4! 



brook and salmon trout ; rather more of the former 

 than of the latter. I can account for this on no other 

 ground than from the fact that as a rule the brook- 

 trout inhabit small bodies of water, thereby render- 

 ing the possibilities of inter-breeding greater than 

 with other fish. In any event, the percentage is so 

 small that it in no sense interferes with the results 

 of artificial propagation. The two kinds of malform- 

 ations most frequent among the young fry, are 

 those with two heads and one body or trunk, and 

 those known as Siamese Twins, from the fact of 

 their being connected similarly to that celebrated 

 monstrosity. Rare cases occur, where the fish have 

 three heads on one body. Among the millions of 

 young fry that have passed under my observation, I 

 have seen but two specimens of this kind. 



The fry are also subject to all sorts of curvatures 

 of the back-bones. The curves are found at nearly 

 all degrees, from a slight bend to a complete circle 

 the head and tail meeting. Some that are affected 

 in this way are able to swim, but they go round and 

 round in a continuous circle. Others are so knotted 

 as to be unable to make any progress whatever. 

 The cause of death in these instances is the ab- 

 sorption of the yolk sac which is attached to each 

 young fry. While this remains, food is unnecessary, 

 and it will sustain life in the deformed fry for about 

 thirty days, and in a healthy fish for about forty days. 

 When it is gone, the former die of starvation, as they 

 are unable to find food. For the sake of the experi- 

 ment, I have tried to prolong their lives by careful 

 feeding, and have succeeded in so doing for about 

 sixty days, after which they succumb. One pecu- 



