PLATE 1 



EXPLANATION OF FIGURES 



All drawings were made with camera lucida, Spencer homogeneous immersion 

 lens 1.8 mm., Zeiss no. 12 compensating ocular. All, except figure 6, were then 

 enlarged two diameters, giving a magnification of 5800. In reproduction, the 

 drawings have been reduced one-third. 



1 and 2 Late anaphases from intestinal epithelium of Culex pipiens, showing 

 six pairs of chromosomes passing to each pole. Figure 1 from stomach ffig. 33, 

 region 8) . Figure 2 is from Dr. Steven's slide, position not known . Note pointed 

 tips of Vs. Compare 31 from same individual. 



3 and 4 Telophases from stomach (fig. 33, region 6). 



5 Early telophase showing two lagging chromosomes. This cell is from the 

 same individual as 2 and 31. Position not determined but probably stomach. 



6 Resting stage from stomach (region 7) showing chromatin scattered about 

 periphery of nucleus and collecting around the nucleolus. The magnification 

 is one-half that of .all other figures. Compare with Miss Taylor's 'clock face 

 figure.' 



7, 8, and 9 Very early prophases showing successive stages in the formation 

 of three separate vesicles containing the chromatin threads. Figure 7, from 

 stomach (region 6). Figure 9, from colon, (region 2). Figure 8 shows a cell 

 about to disintegrate. Note the vacuoles, V, V, just appearing in the cytoplasm 

 and the break in the nuclear wall. 



