390 



THE AMERICAN NATURALIST 



[Vol. LIII 



ceeding group, characterized on a smaller percentage- 

 increase, gave a correspondingly smaller annual produc- 

 tion, until, when we reach ''<0 per cent.," the group 

 manifesting a decroasG in mean egg-weight, we find a 

 mean annual production of only KM) eggs. When the 

 flock is divided according as tlio mean Y)ercentage of in- 

 crease is more than G, or less than G, we find that in the 

 high-percentage group there are 13 hens with a mean 

 annual production of 138 eggs, while in tlie low-percent- 

 age group there are 24 hens with a mean production of 

 114 eggs. In other words, upon the division point of G 

 per cent, increase, one may separate about one third of 

 the flock whose annual production is 15 per cent, higher 

 than the flock average and 21 i)er cent, higher than the 

 mean production of the remainder of the ])irds. 



If the reader will now make a comparison of the results 

 reported in Tables I and III, it will be seen that the corre- 

 lation demonstrated through the eni])loyinent of the "ten- 

 egg method" is as clearly establi-hod, and a^ valuable 

 from the }>ractical point of view, as tlie correlation demon- 

 strated through the u>e of a full month's production. 



VII 



In view, therefore, of these results obtained from the 

 weighing of ten eggs at the period of the vernal weight 

 maximum, it seemed desirable to ascertain whether the 

 same "ten-egg method" at the period of the autumnal 

 weight maximum w-ould also serve to distinguish a group 

 of hens characterized by the possession of higher pro- 

 ducin<>' ability. Accordingly the production data for 

 Septeinbei- were analyzed from this {)oint of view. 



In e\|i!<-.ti;iti<.ii nf the September results, however, sev- 

 eral puitit> -hould 1)0 noted. In the first place, although 

 Septciiilx'r in-.Mhu'tion represents a definite mode in the 

 annual prochK lioii curve when plotted on monthly ordi- 

 natev, in the ca<e of the flock studied tho month ])ro- 

 duction falls considerably short of the April pro.liK-t ir)n. 

 In April all members of the flock, without (■\<-('pnon, 

 were laying. In September there were four hcii^ that did 

 not lay at all ; and three hens laid only three eggs or less. 



