490 
Max Morse 
jiart of the nucleus leaving a clear space, free from chromatin, at 
the looped portion of tbe tlireads and between tbem and the nuclear 
wall. At first the threads are crinkled as they emerge from their 
tightly compacted condition, but they soon become straight, so that 
in an optical section (fig. 12), each loop cnts the plane of observation 
twice, once for each arm of the loop. In such an optical section, 
approximately sixty points of intersection mav be counted as au 
average. It is quite impossible to determine the number exactly 
owing to the attenuated condition of the threads and to their number. 
All the threads at tliis stage are nearly of equal thickuess. For a 
time, they increase somewhat in staining power (fig. 13) although 
there is little alteration in thickuess. 
We sliall pause in the discussion of the ordinary chromosomes 
uutil we bring the odd chromosome and plasmosome up to this 
point. 
b) The odd chromosome. As the chromosomes of the telopha9e 
of the spermatogonia fade and are resolved iuto threads, one of their 
number does not participate in the thread formation nor in loss of 
staining capacity (fig. 7) except to a slight extent, but persists to 
form the chromosome-nucleolus of this and later stages. For a time 
fig. 8), it retains its spherical shape, although it may become some- 
what irregulär in outline. Soon, liowever (fig. 9), it assumes a pear 
shape, the pointed end becoming apparently continuous with one of 
the threads. In figure 10, it is seen endwise. At the advent of the 
polarization stage (fig. 11) it becomes oriented so that its pointed end 
lies towards the pole while the body as a whole lies near the pole 
end of the nucleus. The chromosome-nucleolus never lies within the 
mass of threads, but invariable on their periphery, applied closely to 
the nuclear wall. A longitudinal split now bccomes evident (fig. 11) 
in the body, which clearly divides it into two equal moieties wheu 
seen from the blunter end (fig. 12). It participates in the increase of 
staining power sliown by the threads (fig. 13). Düring these later 
stages, it may sometimes become somewhat irregulär in outline 
(fig. 14), although it always retains its characteristic pear shape. 
c) The plasmosome. The plasmosome appears at the same time 
as the chromosome-nucleolus and closely associated with it (fig. 7). 
It is small at first, conspicuously smaller tlian the plasmosome of the 
spermatogonial stages, which frequently persists up to this time 
(fig. 7), lying in the cytoplasm. Düring the contraction stage (figs. 9 
and 10), it seems to be closely applied to the chromosome-nucleolus 
