206 



POULTRY PRODUCTION 



of the hen was secured as before, and that of the eggs by 

 breaking the shell immediately over the embryo and inserting 

 the bulb of the thermometer. The results are tabulated in 

 Table XXI. It will be noted that the temperature of the 

 egg is influenced throughout by the temperature of the fowl, 

 and that while there is an average difference of over 3° the 

 first four days of the incubation period, there is an average 

 difference of lf° the last, four days of the period. This 

 difference is doubtless due to the increasing animal heat 

 generated by the growing embryo. 



Table XX. 



I 



II 

 III 



IV 



I 



II 

 III 



IV 



15 



16 



104.8 

 105.0 

 104.2 

 105.0 



18 



20 



105.0 

 105.0 

 103.5 

 104.5 



104.5 

 105.0 

 103.0 

 104.5 



105.5 

 104.0 

 104.0 

 105.0 



105.0 104.5 105.0 



104.5 104.0 105.0 



105.0 105.0 104.5 



103.5 104.0 104.5 



14 



105.5 

 104.2 

 103.6 

 1(J5.0 



It should be recognized that this is but a single test, 

 which should be supplemented by many further tests before 

 drawing too definite a conclusion. It leads the way, however, 

 to an understanding of the principle of governing the tem- 

 perature of the incubator. That principle is to carry such 

 a temperature in the egg chamber that the egg will be as 

 nearly as possible the same temperature as when under a hen. 



