456 HAYATO ARAI 
licles is considerably increased as compared with their number 
before puberty. This finding is different from that of Loeb, but 
the difference may be due partly to the difference in the animals 
used. However, it seems to me more probable that the ap- 
pearance of the corpora lutea gives an impulse to the degenera- 
tion of the small follicles. 
At any rate, the percentage of degenerated follicles after 
puberty is higher than before puberty, as is shown in the above 
calculation, where the number of degenerated follicles is as high 
as about 16 per cent of the total number of ova. Therefore, the 
decrease in the number of ova according to the age seems to be 
caused principally by the degenerated follicles. We can neglect 
the ripened ova, eight to ten of which are discharged into the ovi- 
ducts at every ovulation period, as this number is insignificant 
in relation to that of the degenerate follicles. 
Sobotta and Bureckard (10) stated that in white rats the maxi- 
mum number of ripe ova which enter the oviducts is altogether 
thirteen from both ovaries and the minimum is four, although 
eight to ten ova are more usual. The maximum number of ripe 
ova from one ovary is said to be eight. 
According to Donaldson, the largest litter noted in the com- 
mon albino is seventeen, while Kolazy (’71) also reported a litter 
consisting of seventeen young. 
According to these observations, the highest number of ova 
discharged into the fallopian tubes is seventeen and the lowest 
is four. Usually it is eight to ten. The average number of the 
mature follicles in the ovaries at several ages, however, is twenty- 
one, and therefore about half of these mature follicles must rup- 
ture and discharge their ova into the oviducts, and the remaining 
half must undergo atresia. 
