408 EDMUND B. WILSON. 



PLATE II. 



(Pentatoma senilis, except 25.) 



FIG. 17. First spermatocyte-metaphase chromosomes from a single spindle, 

 with chromatoid body, artificially spread out in a series for comparison, the large 

 bivalent seen sidewise; 18, a-/, the XF-pair in successive stages, all in the same 

 position with reference to the spindle (as in Fig. 17), a and b from metaphases, 

 c-f from anaphases; 19, a-e, the large bivalent in successive stages, a-d from 

 prophase-nuclei, e from metaphase; 20, a-e, corresponding series of small bivalent, 

 a-c from prophase-nuclei, d, e, from metaphases; 21, tangential section of first 

 division showing XF-pair and chromatoid body; 22, 23, second spermatocyte- 

 telophases, with chromatoid body; 24, the same without chromatoid body; 25, 

 the same with chromatoid body near one pole, Pentatoma juniperina; 26-29, early 

 growth-period; 30, confused period; 31, middle prophase; 32, late prophase, all the 

 chromosomes foreshortened. 



