McAllister—-Cytology and Embryology. 657 
Figure 10. JSTueleus at a more advanced stag© of contraction. 
Chromatin threads of two sizes can be seen here. 
Also definite double strands. 
Figure 11. A tangential section of the nucleus represented 
in figure 10. Evidence is to be seen here of the ap¬ 
proximation of two thin spirems to form one thick 
spirem. 
Figure 12. A portion of a nucleus entering into synapsis 
showing chromatin threads of different diameters. 
Figure 13. The fully contracted synaptic knot. 
Figure 14. A tangential section from the synaptic knot in the 
above figure. The double nature of the spirem is 
clearly evident in a part of the strands. 
Figure-15. A tangential section from! another synaptic knot, 
showing doubleness. 
Figure 16. A nucleus at the time of recovery from synapsis. 
The spirem shows some evidences of doubleness which 
may however be due to the rows of darker bodies 
along the periphery of the threads. 
Figure 17. A post synaptic stage. The spirem is not quite 
uniformly expanded. The free ends showing are cut 
ends of the section. 
Figure 18. A surface view of a nucleus in the uniformly ex¬ 
panded condition. 
Figure T9. A median view of a nucleus in very early stages 
of the second contraction. The free ends to be seen 
here are ends of spirem thread which pass out of the 
plane of the section. 
Figure 20. A view of a section of a nucleus entering into the 
second contraction, showing the distribution of the 
spirem threads at this time. The first longitudinal 
splitting is clearly evident here. 
Figure 21. A nucleus in the second synapsis. The spirem is 
partly aggregated in the center only. 'Segmentation 
is taking place in the region of the periphery of the 
nucleus. This figure is from a nucleus uncut by the 
razor. !Nbt all the spirem is drawn however. 
