NOWLIN: CYTOLOGICAL STUDIES OF FEMUR-RUBRUM. 403 
an unequal growth of nucleus and cytoplasm now, the nucleus 
gaining on the cytoplasm, as seen in figures 13, 14, 15. At 
the same time the chromatin moves to the nuclear boundary, 
where it forms a darkly staining band. The cytoplasm begins 
to elongate at one side of the nucleus until a condition seen in 
figure 17 is reached. The remainder of the marked meta- 
morphosis of the cell consists of a condensing of material un- 
til a small, elongated nuclear head remains, and a long vibra- 
tile fiber. (Fig. 25.) 
Melanoplus differentialis. 
A glance at plate 31 will show that differentialis follows very 
closely the description for femur-rubrum. There are from one 
to two and occasionally three rings seen in an equatorial plate 
of the first spermatocyte, and there is a tendency for most of 
the larger chromosomes to form rings in the prophase. Thus 
we may see three or four rings at one time. Differentialis is 
the most favorable material of the Melanoplus group thus 
far investigated. The chromosomes are a little larger than 
femur-rubrum and have the advantage of not crowding so 
much. 
Melanoplus atlanis. 
Figures 1 to 12, plate 32, show spermatocyte divisions in 
M. atlanis. A comparison of this species with the two pre- 
ceding shows that the chromosomes are more irregular in 
form, but as to general behavior, numbers, etc., are the same. 
Melanoplus packardii. 
Plate 32, figures 13 to 24, show a few of the stages of divi- 
sion in M. packardii. The chromosomes of this group are smaller 
than any of the preceding, but in general behavior and form 
are similar. 
SUMMARY AND DISCUSSION. 
In the four species of Melanoplus set forth in this paper we 
find a close similarity in form and behavior of the chromo- 
somes in the different generations, and an identity in number 
throughout. That is to say, twenty-three spermatogonial 
chromosomes and twelve spermatocyte. The counts in the fe- 
male cells did not give more than twenty-two, but there is 
much room for doubt, owing to crowded plates. The results 
of this paper tally with those on Melanoplus bivitatus Say 
(08). 
