128 BERTRAM G. SMITH 



haemotoxylin than the others, and in sections stained with the 

 borax-carmine Lyons-blue picric-acid mixture the included 

 granules take the cytoplasmic stain more deeply. 



The follicle cells later become greatly elongated, and the cyto- 

 plasm takes the form of a faint meshwork with large spaces. 

 Ingestion of yolk continues at the inner ends of the cells, while 

 the remainder of the cell functions as a long tube to convey the 

 products of digestion to the periphery. The follicular layer 

 remains one cell in thickness until the cells have reached a length 

 of about 250 ii] with a further increase in thickness it becomes 

 broken up into a meshwork of cells, amongst which are numerous 

 capillaries. Ovocytes have been found in which this meshwork 

 of cells reaches nearly to the center, and the remaining yolk is very 

 small in amount. 



In the adult female occasional eggs, though of full size, fail to 

 escape from the ovary. Judging from their external appearance 

 these ovocytes undergo resorption in the manner just described. 

 A somewhat similar process of resorption has been described in 

 the eggs of cyclostomes and fishes (Biihler, '02) . 



4- The organization of the egg shortly before the appearance of the 



germinal vesicle at the surface 



At this point it may be well to summarize briefly the condition 

 of the ovocyte in the stage immediately preceding the appear- 

 ance of the germinal vesical at the surface (see fig. 26) . 



The egg lies within a triple-walled follicular sac whose cellular 

 membranes have undergone little change since they first became 

 well established. The stalk of the follicle, and in general the 

 animal pole of the egg, lie toward the periphery of the ovary. 



The zona pellucida persists unchanged, except for a shght in- 

 crease in thickness; the zona radiata shows signs of atrophy, and 

 in some cases is assuming the character of a simple cell wall. 



The nucleus or germinal vesicle has migrated from the center 

 of the egg to a position near the periphery, ordinarily on the side 

 toward the stalk of the follicle. During the migration of the 

 germinal vesicle a cone-shaped mass of dense cytoplasm has 



