554 MR SHAW'S EXPERIMENTAL OBSERVATIONS ON THE 



net being employed with certain success. Before proceeding to take the fish, I 

 formed a small trench in the shingle by the edge of the stream, through which I 

 directed a small stream of water ft-om the river 2 inches deep. At the end of 

 this trench, I placed an earthenware basin of considerable size, for the purpose of 

 ultimately receiving the ova. I then, at one and the same instant, enclosed both 

 the fish in the hoop, allowing them to find their way into the bag of the net by 

 the aid of the stream. In capturing these fish, I considered myself fortunate in 

 securing them by one cast of the net, for, in conducting the experiment of artifi- 

 cial impregnation, it appeared to me to be very desirable that the male should be 

 taken, with the female of his own selection, at the very moment when they were 

 mutually engaged in the continuance of theu- species. To take a female from 

 one part of the stream and a male from another, might not have given the same 

 chance of a successful issue to the experiment. Having drawn the fish ashore, I 

 placed the female, while still alive, in the trench, and pressed from her body a 

 quantity of ova. I then placed the male in the same situation, pressing from his 

 body a quantity of milt, which, passing down the stream, thoroughly impregnated 

 the ova. I then transferred the spawn to the basin, and deposited it in a stream 

 connected with a pond previously formed for its reception, which, however, I 

 have not considered it necessary to represent in the accompanying plan. The 

 temperature of this stream was 39°, of the river from which the salmon were 

 taken 33°, and of the atmosphere 36°. The skins of the parent sahnon are now 

 in my possession. 



On examining the ova on the 23d of February (fifty days after impregnation), 

 I found the embryo fish distinctly visible to the naked eye, and even exhibiting 

 some symptoms of vitality by moving feebly in the egg. The temperature of the 

 stream was at this time 36°, and of the atmosphere 38°. On the 28th of April 

 (114 days after impregnation), I found the young salmon excluded from the egg, 

 which was not the case when I visited them on the previous day. The tempera- 

 ture of the stream was then 44°. The ova, which for some time previous to being 

 hatched, had been almost daily in my hand for inspection, did not appear to suf- 

 fer at all from being handled. When I had occasion to inspect the ovmn, I placed 

 it in the hollow of my hand, covered with a few drops of water, where it fre- 

 quently remained a considerable time without suffering any apparent injury. The 

 embryo, however, while in this situation, shewed an increased degree of activity 

 by repeatedly turning itself in the egg, an action probably produced by the in- 

 crease of temperatiire 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 exception 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 experi- 

 ments, arising, I apprehend, from a deposition of mud, the same result having 



