30 SALMONID.E. 



them on the previous day. The temperature of the stream 

 was then 44. The ova, which for some time previous to 

 being hatched, had been almost daily in my hand for inspec- 

 tion, did not appear to suffer at all from being handled. 

 When I had occasion to inspect the ovum, I placed it in the 

 hollow of my hand, covered with a few drops of water, where 

 it frequently remained a considerable time without suffering 

 any apparent injury. The embryo, however, while in this 

 situation, showed an increased degree of activity by repeat- 

 edly turning itself in the egg, an action probably produced 

 by the increase of temperature arising from the warmth 

 of the hand. 



" On the 24th of May (twenty-seven days after being 

 hatched), the young fish had consumed the yolk, but in a 

 few days afterwards the whole of this family, with the excep- 

 tion of one individual, were found dead at the bottom of the 

 pond, a circumstance which has occurred more than once in 

 the course of my experiments, arising, I apprehend, from a 

 deposition of mud, the same result having previously taken 

 place, when the pond had not been sufficiently imbedded 

 with gravel. 



" To show the effects of increased temperature in hasten- 

 ing the development of the infant fish, I may relate an ex- 

 periment which I made upon a few of the same ova, from 

 which this family proceeded. On the 20th of April (one 

 hundred and six days after impregnation), finding the ova 

 alluded to unhatched, and the temperature of the stream 

 being 41, I took four of them and placed them in a tumbler 

 of water, covering the bottom with fine gravel, in which I 

 imbedded the ova. I then suspended the tumbler from the 

 top of my bed-room window, above which I placed a large 

 earthenware jar, with a small spigot inserted in its side, 

 from which I easily directed a stream of pure spring water 

 into the tumbler. The waste water was carried out at the 



