20 J. BRONTE OATENBY 



large lower area formed of the heavy nucleolar deutoplasm, 

 forming by far the largest separate part of the centrifuged 

 oocyte. 



These areas are shown in Text-fig. 1. The nucleus generally 

 lies in the middle layer. The mitochondria appear to be lighter 

 than the nucleolar deutoplasm and take up a position in an 

 area above the latter, m in Text-fig. 1, l)ut are also found 

 throughout the lower area. 



Around the exposed periphery of the egg, the cortical lamellae 

 are beautifully apparent, especially in Benda preparations 

 (cL in Text-fig. 1). It is from these lamellae that the substance 

 of the fertilization membrane is produced. See also lamellae 

 in PI. 4, fig. 27, cl. 



9. Cells Found in the Male, intermediate between 

 Spermatocyte and Oocyte. 



In the coelom of the male Saccocirrus are found large cells 

 packed with yolk-spheres ; these large cells often fill up all 

 the coelomic space in the mid region of the l)ody, excepting 

 for the areas occupied by developing spermatozoa. 



Occasionally one finds large isolated cells lying completely 

 surrounded by and shut in between the large yolk-cells. These 

 isolated cells were once young spermatocytes, which, during 

 growth of the yolk, have become shut off. That this is so 

 is indicated by an examination of a sufficient number of 

 Saccocirrus males. 



Now these isolated cells are sometimes remarkable for the 

 fact that they show a rough resemblance to oocytes at the 

 stage of nucleolar extrusion. In PI. 1, fig. 3, is drawn such 

 a cell. The group of yolk-granules is at y, several groups of 

 fine mitochondria are at m, m, while the nucleus is found to be 

 in the process of extruding large peculiar nucleoli, nlx. In 

 this one section the nucleus showed four pieces being extruded, 

 two other nucleoli inside the nucleus, and one piece on the 

 lower right of the cell akeady detached fi-om the nucleus ; 

 an examination of the larger nucleoli in fig, 3 shows that they 



