﻿Coutr. toward the Embryol. and Anat. of Pol. pallipes (Hyinenopt.). 135 



of the nuclei in all parts of the egg. We find, however, that only 

 in the late stages is this noticeable and then not niore so than the 

 differenees in size between nuclei of different eggs. It must be 

 borne in mind, when we meet with these and other slight variations, 

 that we are working with eggs collected indiseriniinately from the 

 nest, which were destined to develop into wasps of different sexes. 

 Until proved to the contrary, we see no reason why the fate, as to 

 its sex, of an egg could not influenae certain minute differenees in 

 the strueture of parts of the egg, more especially in the nuclei. 



Eeturning to the aecount of the resting nuclei we find many of 

 them showing a distinet centrosome (Figs. 9 and 10); this appears as 

 a small, darkly stained granule, situated but a short distance without 

 the nuclear membrane. We could not find that it had any definite 

 position relative to that of the nucleus. Noack (42) has shown that 

 the centrosome present in the cleavage nuclei of Calliphora is in 

 front of the nucleus; that later it divides, the halves separating and 

 going to either side. In Polistes a Single centrosome surrounded by 

 a mass of archoplasm was present, a Single one dividing or the two 

 which would result from such a division not being observed. The 

 boundary between the archoplasm and the surrounding cytoplasm 

 was not such as could be represented by a distinet line; the former 

 stained darker and passed rather abruptly into the lighter colored 

 cytoplasm surrounding it. The archoplasm had in some instances a 

 regulär outline (Figs. 8 and 10); in others a distinet radiation was 

 observed (Fig. 9) which penetrated to different depths the surrounding 

 cytoplasm. While not common, two nuclei have been observed within 

 the same mass of cytoplasm (Fig. 11). What we have said concern- 

 ing the resting nuclei holds good for those taken from early or late 

 pre-blastodermic stages, and also for either cleavage or yolk nuclei. 



A study of the dividing nuclei shows that the chromosomes are 

 small irregulär bodies the minuteness of which makes a determination 

 of their exaet size and number difficult. In an equatorial plate 

 stage we find spindle fibres passing towards each centrosome and 

 converging within the surrounding archoplasm. In this stage a 

 centrosome is clearly seen at each pole surrounded by archoplasm 

 from which radiates a number of distinet astral fibres (Figs. 14 and 15). 

 The distance between each centrosome and the adjacent margin of 

 the cytoplasm is generally short and in this direction, away from 

 the plate, the astral fibres are short, often hardly perceptable. The 

 fibres all remain within the cytoplasm and their length is often 



