PLATE 4 
EXPLANATION OF FIGURES 
36 Four sections of the nucleus of a spermatocyte during the prophase of the 
first maturation division, showing the X-complex and fifteen bivalent euchromo- 
somes. 
37 Same stage; all the chromosomes represented in the same plane. The con- 
densation of the M-chromosomes is not so advanced as in the preceding figure. 
38 Spermatocyte in the early prophase showing splitting of the euchromo- 
somes, which have been disposed in a series in figure 39, according to their de- 
gree of condensation. 
40 Euchromosomes from different spermatocytes showing differences in the 
process of splitting. The chromosomes represented in b and d are Y-shaped 
chromosomes seen endwise. 
41 X-complexes drawn from cells in the early prophase. The M-chromo- 
somes are united directly with each other in f, the X-chromosome occupying the 
end of one of the arms of the V-shaped complex. 
42 to 45 Metaphases of the first division in polar view. 
46 Four optical sections of a metaphase in lateral view, showing attachment 
of the spindle fibers in the X-complex. 
47 Polar view of a metaphase in which the X-chromosome has failed to con- 
dense, appearing as a U-shaped body. 
48 Three complexes drawn from metaphases. The X-chromosome has failed 
to condense in b. Inca single small chromosome is seen. 
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