414 HAYATO ARAI 
right ovary is smaller, it seems reasonable to infer that the right 
ovary may be slightly retarded, and consequently is smaller and 
also contains more ova than the left, as the number of ova 
decreases with increasing age. 
This conclusion seems to be supported by the fact that previ- 
ous to the first appearance of the corpora lutea at sixty-four days 
40000 
Number of ova (total) eee Se SSSR SSeS SSeS See R sees eee 
i [ine a fo |] ait 
ef i ef fe aa es a | a Qe ise 
SE) [ef er inti i | | a ro a 
8 ie eta ine ima a a 
GSanGae SESSS0Ra Ty 
35000 
30000 
: 
H 
20000 
lat 
aga 
fT BESSGRSh0 
ERLe2SENeeNeee a | [nf i i i a fi 
ReaD TB Pet [| FEE 
sf SY  a TNgV fae fea et fd a ao 
[| Se ke Hoao 
600 700 800 900 1000 
Age—days 
Chart 1 Showing the total number of ova in both ovaries of the albino rat 
at different ages (in detail). 
the average relative weight of the right ovary is 0.88, while after 
this age it is 0.91 (bottom of table 1). l 
On the number of ova in relation to age 
In table 2 the data on the thirty-nine rats are given. 
As will be seen from both table 2 and chart 1, the total num- 
ber of ova counted in both ovaries one day after birth was 35,105. 
This number decreases rapidly to 11,000 at twenty days, after 
which there is a very slow decrease to about 10,000 at sixty-four 
