TEMPERATURE SHOULD BE LOW. 97 



fish should not be hatched out too soon, too 

 early in the year, and acquire its mature 

 growth before the food on which it subsists 

 is to be found, but that they should both be 

 produced simultaneously. Keep therefore 

 your temperature low, or you will hatch your 

 fish out too early in the season. This is one 

 of the first results I obtained. Thus " The 

 Field" window began to hatch on the 16th 

 of January, at the temperature of 52° to 55°. 

 The Zoological fish did not begin to hatch 

 till Jan. 21, the temperature being from 48° 

 to 50°. The temperature made all this 

 diflference ; but mark again another and 

 most important difference. The fish which 

 take the longest time to hatch are al- 

 ways the strongest fish of the two ; a 

 fact which agrees with Mr. Ponder's obser- 



