The Chromosomes of Gryllotalpa Borealis Bunn. 143 
ing twelve chromosomes and the other eleven. These two kinds further 
differ in that one contains a large idiochromosome and an odd chromo- 
some, and the other a small idiochromosome. Fig. 1 K and L are ana- 
phase figures from the same cell showing the manner of the first division 
and the two kinds of chromo- 
some groups which pass to the 
secondary spermatocytes. 
Metaphase plates of the 
second maturation dmsion show 
the same number and the same 
size relations as the anaphase 
figures of the first division (Fig. 2 
1 and J showing the twelve 
dass and Fig. 2 K and L the 
eleven dass). WTiüe my material 
does not show good anaphase 
figures of the second division in 
polar \üew, side views of such 
figures (Fig. 2 0) indicate that 
aU the chromosomes divide. 
Fig. 2 M, N and 0 shows clearly 
the division of the odd chromo- 
some, while Fig. 2 H shows the 
division of the small idiochro- 
mosome before the others. The 
number and size relations of 
the chromosomes in the male 
and female groups make it con- 
clusive, it seems to me, that all 
the chromosomes must divide 
in this division. The male 
number is twenty-three and one of these is a small idiochromosome 
while the female number is twenty-four and there are no small chromo- 
somes present. Thus we have two classes of spermatozoa differing as 
did the secondary spermatocytes in that one dass contains eleven chro- 
mosomes and the other twelve, and in that the eleven dass contains 
a small idiochromosome and the twelve dass a large idiochromosome 
plus an odd chromosome. Judging from the male and female groups 
these two classes must be respectively male and female producing and 
the fertilization formula as follows: 
Fig. 2. 
(f'ryllotalpa borealis Burm. B, C, E and F, side 
views, metaphase plate, first division; 6', anaphase, 
side view, first mataration division; Hy metaphase, 
side view, second maturation division; / and J, meta- 
phase plate, polar view, second division, showing tbe 
12 chromosome dass of secondary spermatocytes; A' 
and Ly metaphase plates, polar view, second division, 
showing the 11 chromosome dass of secondary sper- 
matocytes; My y and 0, side view, second division, 
showing the division of the odd chromosome; P, second 
division, anaphase, polar view, showing that all the 
chromosomes divide in the 11 chromosome dass of 
secondary spermatocytes. 
