That synapsis or chromosome reduction takes place during the 
synizesis or contraction phase is evidenced by the fewer and coarser 
(double) postsynizesis loops (figs. 12 to 13). The reduction process 
is here unmistakeably one of parasynapsis. As noted for a number 
of forms, the synizesis loops are in height about half the diameter 
of the nucleus. These then become freed at one end, lengthen out 
and unite end to end in pairs. In the bat, the process of end to end 
conjunction is coincident with a close side by side approximation 
(figs. 10 to 13). The postsynapsis thread and prophase chromosomes 
are distinctly double beaded structures (figs. 16 to 19). It appears 
also that in the bat the side by side union has frequently already 
Fig. 4. Small resting primary spermatocyte. The nucleus is vesicular, with a 
delicate more or less chromatic wide-meshed reticulum and a bi-lobed (or frequently 
spherical) chromatin (chromosome) nucleolus. 
Fig. 5. Small resting primary spermatocyte with two chromatin nucleoli: the 
result of a separation of the bi-lobed body. 
Fig. 6. Large resting primary spermatocyte, showing a bipartite chromatin nucle- 
olus (accessory chromosome). 
Fig. 7. Synizesis phase, showing the polarization of the intensely chromatic 
synizesis mass on the idiozome; and the chromosome nucleolus connected with the mass 
by a chromatic thread at the opposite pole. 
Figs. 8 and 9. Successive early stages in the disentangling of the compactly 
massed synizesis thread, showing also the attached chromosome nucleolus. 
Fig. 10. Later stage in the same process, showing a more open network (looser 
wound thread), two chromosome nucleoli, x (separation products of a single body), and 
a phase of synapsis. 
Fig. 11. Synapsis stage, showing coincidence of the process of telo- and para- 
synapsis; also the chromosome nucleolus at the right. Note that the nucleus of the 
synizesis stage is no larger than that of the earlier resting stage (figs. 4 to 6). 
Figs. 12,13, 14 and 15. Later synapsis stages, showing also the persisting chromatin 
(chromosome) nucleolus. 
taken place, or occurs coincidently with, the opening out of the 
synizesis loops (figs. 11 and 13). Accordingly, here synizesis and 
synapsis (parasynapsis) seem coincident events. How these bivalent 
