Contr. towards the Embiyology and Anatomy of Polistes pallipes. 207 



Single one often appears split (Fig. 50). We are unable to offer any 

 explanation as to its origin or fate but merely record its presence 

 in Polistes. In early larval stages it seemed that its origin could 

 be traced from a solid body (yolk-nncleus?) the central part of which 

 dissolving left the ring. Some bodies with ligbter central parts were 

 Seen but not enoiigh to give any surety of the development of the 

 rings in this way. They appear to be present in the center of the 

 cell (Fig. 100) but this is, we believe, due to the different view we 

 have of them. Two dividing cells were also found which showed 

 a ring between them (Fig. 99), and from one pole of each mitotic 

 figure a fibril passed to the ring. 



Summary. 



In the embryos and very early larvae each gonad is a synctium 

 with a number of nuclei similar in structure. Very early in larval 

 life cell boundaries appear. 



The ovarian tubules develop; they at first contain cells similar 

 in structure but differing in size, the largest being in the proximal 

 half of each tubule. 



Each ovarian tubule when first formed, ovary A, has a distal 

 half, in which the cells and their nuclei are elongated, and a proximal 

 half, where they are larger and rounder. This distal part becomes 

 proportionately smaller and smaller; the cells in it never show the 

 variations in structure that are seen in those of the proximal part. 



In older larvae, ovaries A and B, we find each tubule of three 

 parts ; a distal portion in which the cells are very similar in structure, 

 a median portion, where are found the differentiating oöcytes and 

 nurse-cells, and a proximal part, that becomes the oviduct. At the 

 boundary, not real, between the first and second parts most of the 

 cells change from undifferentiated ones; as growth goes on, this 

 boundary is found nearer the distal end of the tubule, i. e. the relative 

 size of the median part increases, of the distal part, decreases. 



As the ovarian tubules grow, the cells in the distal part remain 

 the same; those in the middle portion change in size and in nuclear 

 structure and we can distinguish between oöcytes and primitive 

 nurse-cells, ovaries C and D. The latter cells pass through a number 

 of divisions. As growth goes on. these two kinds of cells become 

 more and more unlike. 



After the repeated division of the primitive nurse-cells have 

 ended, the nuclear structure of all the nurse-cells is similar. For 



14* 



