Jv^o. 628] 



379 



cate alien's producing ability before sbe bas attained tbat 

 stage in life wben economic production ceases ; and wben, 

 even as a breeder, ber furtber producing days are few. 



II 



To tbe casual reader it will no doubt appear preposter- 

 ous tbat a biologist sbould attempt to inea-;ure tbe numer- 

 ical egg-production of a ben l)y n-cifihhip ber eggs, ratber 

 than by counting tbem. But tbe autlior freely admits 

 that tbis ridiculous tbing bas actually been done in his 

 laboi"atories ; and, wbat is more, tbat tbe metbod appears 

 to woi-k: a flock of bens can be di\'idcd into groups, eacb 

 cbaractei'ized by a different mean ])roducing ability, as a 

 result of weighing a certain number of egffs at a certain 

 time in t1ie layin<>- year, and sub>("(in(Mit ly b\- niakinu' cer- 

 tain computations lliererrom. The ronlts drtuMid ui)on 

 tho rclaflfju rrlsfnifi hrtirrrn rr/o-irri^ltt hihI r<i<i-pn,fl nc- 

 fioH „l >riffi > , ut iH nr,rl. of fh,' hiifluf/ >/< nr. Tbe>e point^- 



