392 



THE AMERICAN NATURALIST 



[Vol. LIII 



showing a decrease in egg-weight) gave five hens with a 

 mean production of only 108. When we add to these the 

 hens that laid three eggs or less in September, we obtain 

 a group whose mean production was only 96 ; and when 

 we consider the hens that (1) gave a September produc- 

 tion of 3 eggs or less, and (2) gave a decrease in. egg 

 weight, we obtain a combined group of 12 whose mean 

 annual production was only 101 eggs for the first laying 

 year. 



A comparison of Tables I, II, III and IV thus shows 

 that the last case presents the clearest evidence yet ob- 

 tained for the positive correlation existing between per- 

 centage of increase in egg-weight and total annual pro- 

 duction. The results are more definite than those ob- 

 tained for the "ten-egg test" at the vernal weight maxi- 

 mum, or for the "month test" at either the vernal or the 

 autumnal weight maxima. In other words a test based 

 upon a smaller number of eggs, laid nearer to the absolute 

 mode, gives a clearer indication of innate producina: abil- 

 itv than does a test based upon a larger number of eggs 

 laid m a "scatter grouping" about the approximate mode. 

 This conclusion is m linrnionv witli the views cxprossed 

 b\ CraMn^- and b^ "\\ iNdii' to th. ( Ih < t llm ilu Ix M unit 

 ot time for measui-iiii;' ;i cow s iiiillc-iirodiiciim- ;il)ilit\- is 

 notthe^eal tost, iioi th, llii>\ .1 x t. ^1 iioi tlie 

 seven-dav test, but the one .Inv coiidiictcd when the 

 production readies il- imiiii. A i ij tniciit Iv the meas- 

 urement of egg-pro(lu('ti()ti HI ilic (loiiic.-t ic I owl, consid- 

 ered as a quantitatix ( p(tloiiniiu( u-t- upon a similar 

 basis. 



VIII 



