EMBRYOLOGY OF COCCIDS 81 



Epithelial cells which surround the nurse chamber above never 

 multiply, but those around the egg multiply rapidly and help to 

 accommodate the protoplasmic substance which pours from the 

 nurse chamber above (fig. 15). Soon a constriction becomes 

 evident at the junction of the two chambers (fig. 16), due partly 

 to the ingrowth of the epithelial cells at the base of the nurse 

 chambers and partly to the rapid expansion of the egg and nurse 

 cells. The epithelial cells surrounding the egg chamber are 

 cubical or elongate ovoid in shape and actively divide, while 

 those around the constriction are smaller and spindle shaped. 

 No mitosis was observed among the latter. 



As the constriction progresses, the space through which the 

 two chambers communicate becomes smaller. Consequently, 

 the protoplasmic substance, which has been flowing homogeneously 

 toward the egg nucleus or the gerniinal vesicle, now flows out of 

 this small passage in minute streamlets as molasses does when 

 poured through a funnel into a flask. The nuclei of the nurse 

 cells still increase in size, and change from spherical to egg-shape, 

 the narrow end being directed toward the egg chamber. The 

 chromatin threads become broken into numerous chromatin 

 bodies of different sizes. The nucleus of the egg proper moves 

 toward the center of the egg chamber, but the chromatin threads 

 are still in the paired condition as last described. Their affinity 

 for iron-alum haematoxylin is changed. They now stain so 

 faintly with this dye as to seem almost achromatic in nature. 

 From this time on, the gerniinal vesicle begins to migrate from 

 the center toward the periphery of the egg. During this migra- 

 tion the chromosomes lose their paired appearance and form 

 several small, spherical bodies which become scattered along the 

 nuclear membrane (fig. 17). There is, however, no indication of 

 their being passed out through the nuclear membrane into the 

 surrounding protoplasm, as several investigators of other insects 

 have stated. 



The place where the germinal ^•esicle reaches the peripheral 

 layer is on the ventral surface, midwaj^ between the equator and 

 the posterior pole of the egg. As soon as the clear transparent 

 nucleus reaches the periphery, the surrounding protoplasmic 



