XXX INTRODUCTION. 



and spread over it regularly with the hand one after the 

 other ; and after leaving them exposed in this state to the 

 water for a few minutes, the whole was covered with two or 

 three inches of gravel, and left in the pool. These four pair 

 of fish afterwards emitted voluntarily a small quantity of 

 spawn which had been left with them, and on the 1st of De- 

 cember they were all turned out into the river. On the 3rd 

 of December caught three pair of Salmon, which had already 

 partially spawned in the Ewe : used another bag and basket, 

 treating the spawn in the same way as last described. These 

 fish were then also allowed to deposit voluntarily the little 

 spawn of which they had not been deprived, and afterwards 

 turned out to the river. 



" On the 19th of February examined the ova, and life was 

 plainly observed in the baskets, wire-bags, and unprotected 

 gravel ; both were placed artificially, and were deposited by the 

 Salmon themselves. 



" On the 19th of March, the fry had increased in size, and 

 went on gradually increasing, much in proportion to the tem- 

 perature of the weather. 



" On the 22nd the eyes were easily visible, and a few of 

 the ova had burst, the young fry having a small watery blad- 

 der-like bag attached to the throat. 



" On the 18th of April the baskets and bags were all 

 opened. The bags had become detached from their throats ; 

 the fry measured about three-quarters of an inch in length, 

 and they swam about easily, all distinctly marked as Parr. 



" The baskets recommended by Professor Agassiz proved 

 themselves superior to the wire-bags used by Mr. Shaw. In 

 the latter only about 20 per cent, came to maturity, whilst in 

 the former not above 1 per cent, proved barren ; and in the 

 baskets used on the 5th of December not above 5 per cent. 

 was unproductive. It is impossible to say exactly the propor- 

 tion of ova which came to life either of that artificially im- 



