PLATE 3 



EXPLANATION OF FIGURES 



47 Drosophila obscura, diploid, late prophase, from an embryonic cell dur- 

 ing a late cleavage stage in the egg. 



48 Same, haploid, metaphase, first spermatocyte. 



49 Same, haploid metaphase, second spermatocyte, X-containing class. 



50 Same, haploid metaphase, Y-containing class. 



51 and 52 Calliphora erythrocephala, haploid, metaphase, first spermato- 

 cytes. 



53 to 56 Same, diploid, metaphases, ovarian cells. 



57 Same, somatic. 



58 Same, diploid, somatic, early prophase, entire, or almost entire nucleus, 

 one pair partly displaced in the figure to show all of the threads. 



59 Same, somatic, only part of figure shown. 



60 and 61 Same, somatic, two sections of one nucleus. 



62 Same, somatic, entire or nearly entire nucleus. 



63 Same, ovarian cell, entire nucleus. 



64 Same, somatic, only three pairs represented. 



65 Same, somatic, entire nucleus. 



66 Same, later prophase, ovarian cell, showing separation of the two mem- 

 bers of a pair in late prophase. 



268 



