434 



OVULATION IN THE DOMESTIC FOWL 



which are tabulated with the experimental values. Robertson's 

 tables^ are helpful in solving for x, the calculated number of eggs laid. 



Similar results are obtained with the other principal breeds of 

 birds, the equation for Plymouth Rocks being 



log 



129 - X 



and the equation for White Leghorns 



0.212 {t - 5.9) 



log 



163 - X 



= 0.235 0-6.64)" 



In the equation for White Leghorns, 163 is the value of A since the 

 total number of eggs laid in the year is in round numbers 163 eggs. 

 It takes 6.64 months to lay half this number of eggs. 0.235 is the 

 constant of the reaction. 



It is clear from the tabulation that the agreement between the 

 experimental and calculated values of x (eggs laid) is very good for 

 three-quarters of the laying season — January to August. On the 

 other hand the per cent deviation in the first 2 months (November 

 and December) and the last 2 months (September and October) is 

 very great. The deviations in the last 2 months (September and 



^Robertson, T. B., Univ. California Pub., Physiol, 1910-15, iv, 211. 



