DAVIS: SPERMATOGENESIS. 73 
the middle of the concave side of the nucleus. ‘This is of considerable 
interest, since in the early stage of the primary spermatogonia the 
monosome usually occupies a similar position. 
As the chromosomes disintegrate during the telophase they are, 
in general, oriented with their long axes parallel to a line extending 
through the two poles of the cell. During the resting stage all traces 
of chromosomal limits disappear, but in the succeeding prophase, 
when the chromosomes reappear, they have the same orientation as 
in the telophase of the preceding division. Obviously, the most plau- 
sible explanation of this is that during the resting stage the chromo- 
somes still retain their individuality, although they are not recognizable 
as distinct bodies. Otherwise, it is difficult to see why they should 
reappear with the same orientation as before. Somewhat similar 
phenomena have been described by Rabl (85) and Boveri (’88). 
B.. Arphia tenebrosa. 
The spermatogonia and apical cell are approximately as in Dissos- 
teira. Figure D (p. 72) is a polar view in the equatorial-plate stage 
showing, as in Dissosteira, twenty-three chromosomes. ‘These can be 
easily arranged in pairs, but in this species there are four large pairs; 
the next smaller chromosome is unpaired, the monosome, and this is 
followed by a series of five nicely graded pairs of diminishing sizes. 
There is, as in Dissosteira, a greater difference in size between the 
smallest of the medium sized chromosomes and the two smallest pairs 
than between the successive sizes of the other chromosomes. 
C. Hippiscus tuberculatus. 
The spermatogonia present no essential differences from those of 
Dissosteira. ‘The apical cell, however, differs somewhat in appearance, 
there being in most cases no deeply staining granules in the cytoplasm. 
Usually there is around the nucleus simply a very finely granular 
material, which is comparable to that seen in Dissosteira, but stains 
much less deeply. Moreover, the granular material is distributed 
equally on all sides of the nucleus. In this species the primary sper- 
matogonia usually do not entirely surround the apical cell, which con- 
sequently is in contact on one side with connective-tissue cells. 
In the metaphase twenty-three chromosomes can be distinguished 
which, as in the preceding species, vary greatly in size. Figure F, 
which is a polar view in the equatorial-plate stage, shows that here, 
