Contr. towards'tlie Embiyology and Anatomy of Polistes pallipes. 183 



of the tubule, a condition we do not find in Polistes. Externally, 

 one notices that the distal end of the tubule is pointed, but the 

 proximal end is thicker and rounded (Fig. 6). In studying the larvae 

 of this ag'e, we worked both with ovaries which had been dissected 

 from the body and then sectioned, and also with those which had 

 been sectioned in toto. 



As already mentioned, the distal half of the tubule is filled with 

 eells the nuclei of which are ovoid, here and there, some are found 

 with a neaiiy spherical nucleus; these latter, have no definite position 

 within this part of the tubule but may be median, or near the wall. 

 The nuclei are closely packed tog*ether and mostly restricted to the 

 marginal part of the tubule, lying close to its membrane, this leaves 

 a central portion in which but few nuclei are found. Each nucleus 

 lies with its long axis across the tubule, Leydig (20), Paulcke (25), 

 the cells are generally elongated but, owing to the crowding of the 

 nuclei together, the cell boundaries are difficult to distinguish. 

 Each nucleus, 0,005 mm in length, contains from one to three 

 irregulär nucleoli which do not stain so darkly as the chromatin 

 granules; these latter lie mostly, but not all, in the peripheral part 

 of the nucleus (Fig. 7 h). Achromatin Strands pass irregularly from 

 one to another of these, and, in these small, ovoid nuclei, one or 

 more of them generally extends across it from side to side. 



Near the midie of the tubule, a marked change is noticeable in 

 the shape, both of the cells, and of their nuclei; those, which in the 

 distal half, are shown elongated and with ovoid nuclei, give place to 

 larger and more rounded cells, which contain larger and nearly 

 spherical nuclei. These larger cells occupy all of the proximal halt 

 of the tubule, although, here and there, in this same region a few 

 of the smaller ovoid nuclei can be found. Owing to the larger size 

 of the cells in the proximal half, and to their being less crowded 

 together, we find here a much smaller number than in the distal 

 half. The nuclei of the large cells (Fig. 1 a) are similar in structure 

 to those we found in the embryo, or young larvae. 



In Dijtiscus^ GiARDiNA (8) has described the oöcyte and its 

 nurse cells as remaining together and forming a group, the cells of 

 which, increase in number as mitosis proceeds. Somewhat similar 

 groups were found in the ovary of Polistes in many dififerent stages 

 of development, and it was thought the same arrangement occurred 

 here as in Bytiscus. The explanation given by Giardina (8) seems 

 very plausible, and we should hold a similar view for Polistes^ were 



