ITO Mr Shaw''s Experiments on the Fry of the Salmon. 



while those remaining in the stream did not hatch till the 28th 

 of April, a difference of nearly seven days. At this stage the 

 little fish are so very transparent, that their vital organs are 

 distinctly visible, and when placed immediately under the eye 

 of the observer they present a very interesting appearance. 

 The pectoral fin is continually in rapid motion, even when the 

 fish itself is otherwise in a state of perfect repose. They also 

 begin to manifest an increasing desire to escape observation, a 

 principle wisely implanted in them for their better security, du- 

 ring so feeble and helpless a stage. On the 24th of May (thirty- 

 nine day s after their birth) the fish in the tumbler were completely 

 divested of the yolk, and the characteristic bars of the parr had 

 become visible. At this time they measured nearly one inch 

 in length and appeared to be in perfect health, but fearing 

 that after the yolk was consumed, I should be unable to sup- 

 ply them with appropriate food, I returned them to the pond 

 from which I had taken them on the 20th of April, where they 

 perished with the rest of the family. 



This last experiment proves, that by placing the oy^ under 

 a temporary stream of water in the house, the development of 

 the young may be materially accelerated, while it also shews 

 that they may be kept alive for a considerable time afterwards ; 

 at all events, until the yolk, which I presume to be their sole 

 support at this period, is totally consumed. I mention this 

 fact, because it has been stated by a recent author on the sub- 

 ject, that their life in a state of confinement could not be pro- 

 longed beyond a period of ten days. 



The next experiment, the circumstances of which I have to 

 relate, has been attended with more success than those which 

 I had previously made. The process of taking the adult fish, 

 and all the circumstances attending the impregnation, were en- 

 tirely similar in this case to that already narrated. 



That the pedigree of the young fish may not be called in 

 question, I have preserved the skins of the parents. The 

 weight of the male when taken was 16 lb., and of the female 8 lb. 



The spawn was impregnated and deposited in the stream 

 immediately below the fall pond No. 1. E, on the 27th of 

 January 1837 ; the temperature of the water in the stream 

 beinec 40°, and that of the water in the river 36°. On the 21st 



