2OO ROBERT H. BOWEN. 



EXPLANATION OF PLATES. 



All of the figures have been outlined as far as possible with the camera 

 lucida at an initial enlargement of approximately 3,800 diameters. The out- 

 lines have been extensively corrected and details added free hand. In re- 

 producing, the figures have been reduced uniformly to an enlargement of 

 approximately 3,000 diameters. In every case the method employed in the 

 preparation of the original object has been indicated. 



P, plasmosome; A' and Y, idiochromosomes. 



PLATE I. 



FIGS, i and 2 are from Chlorochroa uhleri; Fig. 3 is from Chelinidea vit- 

 tiger ; Figs. 4, 5 and 6 are from Loxa florida. With the exception of i and 

 2, the original preparations were from material fixed in Flemming and stained 

 with Fe-hematoxylin. 



FIGS, i and 2. Tripolar spindles in the first spermatocyte divison. Some 

 of the chromosomes (stippled) are indicated in Fig. 2. (Osmic impregnation.) 



FIG. 3. Tripolar spindle with normal number of chromosomes in the first 

 spermatocyte division. 



FIGS. 4, 5 and 6. Primary spermatocytes in the later diplotene stage and 

 in the earlier and later growth period, showing progressive fusion of the 

 cytosomes. 



