Ml 1 < TS OF CHANGES IN MKMl M . 



205 



TABLE III. 



I i i i ' re 01 I. KEF FEEDING DURING THE PERIOD OF OLD AGE. 



No detmite time can be set for the appearance >t maturit 

 i In- unset of old age. If a definite favorable r 



tment is an indication of maturity, it m. irly as 



tin- .V't'i or as late as the io2d generation. For the 

 ii \\ould appear about the 6oth generation \\hir! - \\iih the 



>i.itciiH'iit of Calkins that the period of youth <>r imm.mnity 

 (i .\ era .il >nt i lu- first 60 generations. ( )ld .i^r u-u.ill\ -h< .\\ its 

 >rlt .ilmiit tlu- jJ5th generation but it may .ij>i-.ir as i-.ui\ .1- the 

 l.iti- .1- the 2601 h generation. Ol<l ai;r and iinin.itiirity 

 ctitu .inll\ ,iic alike in their response to beef tn-atiiu-ni . They 

 a!-o M-rin tn .i^ree in their relative duration. It" tlu- ju-rind of 

 youth i- prolonged as in series 95 the period '! old age i- likeu i-- 

 Ion. (i than that of the average. Series 95 li\ni rations 



and -ho\\i-d indications of old age during the la-t I 2( > -.--m -rations, 

 it - 117 mat in nl in about the average time of i,n ^c-iu-taiion- and 

 c-\ iK-ni es of age only in the last 40 generation^ the race 

 in the 300 th generation. 



