BEGINNING ARTIFICIAL INCUBATION 59 



and the eggs become largely unhatchable through lack 

 of stamina in the breeding stock. 



Professor Horace Atwood recently expressed, in a 

 bulletin from the West Virginia Station, a universal 

 rule, as follows : " The temperature at which the eggs 

 are kept is the factor which CONTROLS the rate of de- 

 velopment of the embryos." He was applying it to the 



Incubator Cellar, West Virginia Experiment Station 



eggs under incubation, and went on to say : " If the 

 temperature at which eggs are kept (in the machine) is 

 slightly too high, the eggs will hatch before the twenty- 

 first day ; while temperature which is slightly too low 

 may delay the hatch till the twenty-second or the twenty- 

 third day, or possibly even later." We who have prac- 

 ticed artificial incubation did not need that Professor 

 Atwood should tell us this. We know it since long ago. 



