412 HAYATO ARAI 
less complete atrophy. In passing we may note that Riddle’s 
(18) observations on the testes of pigeons and doves show that in 
healthy birds the right testis is larger than the left in most cases, 
so that in birds asymmetry of the gonads appears in both sexes, 
but in opposite senses. 
Since, as we shall see, the weight of the ovaries is influenced 
mainly by the abundance of well-developed follicles and of cor- 
pora lutea, it appears to me probable that the larger ovary 
should be better developed in this respect than the smaller. 
The numbers of ova found in the two ovaries show the fol- 
lowing ratios (table 1). The numbers of ova found in the right 
ovary were compared with those found in the left, taking the 
left as the standard. Out of the thirty-nine cases, seventeen 
show the ratios smaller than one; two show their ratios as 1.00, 
while in the remaining twenty cases the ratios are larger than 
one. 
The averaged ratios in the two lots range from 0.91 to 1.12 
for the right ovary. The average of all the thirty-nine cases 
gives the ratio of 1.03 for the right ovary, thus showing that the 
difference in the number of ova in the two ovaries is very slight: 
From the above it is clear that the right ovary contains ap- 
proximately the same number of ova as the left or a few more, 
despite the fact that it weighs somewhat less. 
The apparent contradiction thus revealed may be due to the 
presence in the left ovary of a greater number of the larve ova, 
as well as of certain stages of the degenerating follicle, and may 
be influenced also by a slight inequality of the corpora lutea on 
the two sides. 
If with these suggestions in mind we consult table 1, it appears 
that the combined numbers for the various classes of larger ova 
(more than 20 yu in diameter) are approximately the same in both 
ovaries, and by consequence the numbers of the smaller-sized 
ova are also approximately equal. It has not been deemed 
necessary to put in the numbers for the ova under 20 u in diame- 
ter, as these may be obtained by subtraction. From the fact that 
while the total number of ova contained in both the right and 
the left ovary is approximately the same, while nevertheless the 
