258 Robert Wilhclm Hcgner. 



tlu; ends oausing these portions to appear darker when seen in surface 

 view. 



The condition exhibited by most of the discs examined is repre- 

 sented in Fig. 3 ; the grannies are not crowded closely together as 

 in the disc described above (Fig. 2), but lie distinct from one another, 

 forming an alveolar-like strnctnre (a network in longitudinal sec- 

 tion). Large vacuoles occur near the outer and inner surfaces of 

 the disc, and in some cases yolk-globules come almost in contact 

 with its upper side. Scattered about in the cytoplasm near the 

 margin of the disc, are a number of its granules which have become 

 separated from the main structure. 



A third disc (Fig. 4) illustrates another condition which is not 

 unusual, especially in the later cleavage stages of the egg. The 

 granules have apparently lost their alveolar arrangement, now being 

 diffused throughout a greater portion of the ''Keimhautblastem." 

 Within this disc are several large vacuoles surrounded by regular 

 layers of granules. 



The granules of the pole-disc are very susceptible to stains ; in 

 hsematoxylin, thionin and gentian violet a color was obtained as 

 deep as that of the chromatin in either dividing nuclei or those in 

 a resting condition ; they stained in orange G more intensely than 

 the surrounding cytoplasm and almost as deeply as the yolk-globules. 

 Other stains failed to bring out any further variations in I he 

 results. 



2. The Genesis of the Pole-Cells. 



Before describing the genesis of the pole-cells of Calligrapha multi- 

 punctata it seems desirable to give a brief account of the maturation, 

 fertilization and early cleavage of the egg. 



Eggs that have just been laid contain polar bodies in various 

 phases of formation ; these are given off into a thickening of the 

 "Keimhautblastem" at a point slightly anterior to the median trans- 

 verse axis of the egg. Here they remain and lator disintegrate. 



The female pronucleus lies in an amoeboid accumulation of cyto- 

 plasm among the yolk-globules. It moves inward and conjugates 

 with the male ])ronucleus at a point level with the polar bodies. 



