VITALITY—UROLEPTUS MOBILIS 295 
The R series came from this weak J series when the latter was 
160 days and 245 generations old, and with only thirty-seven 
days more to live. Thea series came from the P series when the 
latter was 210 days and 291 generations old, and the Q series 
came from I when the latter was 200 days and 316 generations 
old. 
TABLE 3 
Vitality of offspring and age of parents 
STATISTICS OF OFFSPRING STATISTICS OF PARENTS 
1 2 3 SINR: 6 7 8 | 9 io) | a ee 
me ie Rejuvenescence eens of Vitality after offspring 
Series tive divi- % és Series |Relative 
witali sion a Ba, vitality ats soe |) Diva 
tality) rate: : HE Days | BivE | Days | Divi sion 
per cent per cent per cent 
C et | UBB || alse |p eesti ZN 90.9 70 (és) || Ge) Bats |) ala A) 
12 95.0 | 12.5 1.3 WoO) Ib 74.5 70 116 140 USS¢/ || ab 
F CAF loreal) ZAG" (16.3) 7€ 97.7 50 86 | 244) 2638 | 10.8 
A 90.9 | Parent unknown. i 
Wild 
i 89.0 | 16.2) 5.1 SOE |e 94.1 100 143 156 ies |) Talal 
V Sed |) USstey || Bia83 PPA eM| ee 95.0 90 120 197 207 | 10.5 
U2 85.9 | 18.8 | 4.5 26.5}| L 74.5 140 208 70 65 | 9.3 
O (9R50| Looe £25 ? M |Acyst 60 | 108 136 150 | 11.0 
H 78.6 | 16.7} 8.94 638.6)| A 90.9 | 170} 2387 97 46) |) 7.8 
Ui 76.3 | 13.9 | 4.6 PALAU) || 26: 74.5 140 208 70 65 9.3 
L (AnD) e1Ge3) |) 256 15) fy} 1 89.0 120 |- 199 90 1PBS |) 133-0 
D (on Onllamnse | 22 GSS 7/N AN 90.9 100 137 167 1765) 12a 
N GNSS || UGB |) SLO AO 69.0 120 188 a 65 9.0 
ae) 69.0 | 17.4 | 16.3 | 116.4] A 90.9 | 250] 311 17 od | dle 
R 48.1 | 14.8 | 12.7 Com eo 69.0 160 245 37 8 2.2 
a 44.0 | 12.4 | 7.8 0321) 2B 95.0 210 | 291 at 36 | 4.6 
Q op4-) (One |eoo.2 | 30.9))) 1 89.0 | 200] 316 40 6 1.5 
1 Division rate per ten-day periods from start of offspring to last division of 
parents. 
* Average number of divisions in ten days in excess of parents’ division rate. 
Difference between columns 3 and 12. 
- § Percentage increase as compared with the division rate of parents during 
their period of youth. Cf. table 1. For example, the increase in vitality of 
the C series amounted to 12.1 per cent of the division rate of the period of youth 
of the parent A series. 
