PLATE 6 
EXPLANATION OF FIGURES 
70 Four optical sections of a primary spermatocyte during the prochromo- 
some stage. 
71 Beginning of synizesis. The X-complex (X) is already formed and lags 
behind the euchromosomes. 
72 Two cells during synizesis, showing the condensation of all the prochromo- 
somes in the pole of the nucleus nearest to the sphere; in the cell to the left the 
X-complex has been represented. 
73 Polar view of a spermatocyte during synizesis. 
74 X-complexes of spermatocytes during synizesis; the M-chromosomes will 
soon begin to unravel and their outline appears a little ragged. 
75 Polar view of a spermatocyte at the beginning of the unraveling stage. 
The X-complex appears conspicuously. 
76 Two details of the unraveling of the M-chromosomes. 
77 and 78 Leptotene stage, as seen in polar and lateral views of the cells. 
79 and 80 Early pachytene stage. 
81 to 86 Pachytene stage proper. 
116 
