114 W. R. B. ROBERTSON 
the same five long chromosomes. My problem was solved at 
once when I saw that this extra long chromosome paired in matu- 
ration with one of the ordinary chromosomes of the complex, the 
No. 1 (figs. 12-13). 
This unequal pair appears to be of a type different from the 
deficient tetrad just described, and so must be treated separately. 
It is of primary importance in its bearing on questions of synapsis 
and of maturation division. Only two animals having it were 
found, a male and a female. These, and most others of this 
species worked upon, were collected from a spot 75 feet 
square near Waverly, Massachusetts, and are probably related 
individuals. . 
Figures 9 and 10 show cells from normal individuals exhibiting 
the typical condition of the chromosomes in Acridium granu- 
latus. There are two long pairs (6’s and 7’s), two intermediate 
pairs (5’s and 4’s), two short pairs (1’s and 3’s), and the sex 
chromosome, which in size ranks No. 2 in this genus. <A small, 
faintly staining, fragmentary body is shown (dotted) in figure 9. 
It is not present in all cells, and is probably a nucleolar structure 
of some sort. The normal chromosomes paired for the first 
maturation division may be seen in figure 10. Their size re- 
lations are clearly shown there: two large pairs (6, 7), two 
intermediate pairs (4, 5) and two small pairs (1, 3), as well as 
the small ‘accessory’ chromosome (2). 
Figures 11 to 13 are of the abnormal male and female. In 
figure 11 (female) the five, instead of four, long chromosomes 
are clearly shown. The fifth long chromosome (1) appears 
odd because it has no equal chromosome with which to pair. 
The first maturation division in the male (figs. 12-13), however, 
shows it pairing with the small (no. 1) chromosome. In the male 
cells, moreover, it shows a constriction at a region about as far 
from its distal end as the length of the small (no. 1) chromosome 
with which it is paired. 
The other chromosomes are quite normal in these animals 
(figs. 11-13). In the female (fig. 11) there are the two long 
pairs (7’s and 6’s), the two intermediate pairs (5’s and 4’s), the 
short pair (3’s), the 2’s (which are the sex chromosomes and are 
