﻿Contr. toward the Embryol. and Anat. of Pol. pallipes (Hynienopt.). 147 



nuclei have entered the Keiinhautbla stein and the blastoderm is soon 

 to be formed. From an examination of the sections of this egg we 

 find the yolk nuclei evenly distributed thronghout it, and the masses 

 of cytoplasm containing as yet each but a Single nucleus. A number 

 of these nuclei are seen in initosis, similar to that we have already 

 described, and no changes are noticed in their structure which would 

 separate the two kinds of nuclei from each other. One decided 

 change is, however, found, and that is the presence, in the yolk, 

 of nuclei which are dividing amitotically. This bas not as yet been 

 recorded by us in any of the earlier stages, and we get here two 

 methods of nuclear division occurring among the yolk nuclei in the 

 same egg, the mitotic predominating; the amitotic was found only a 

 few times in all the sections of the egg. 



Passing to a somewhat later stage, one in which the blastoderm 

 cells are nearly all formed, we find that the yolk nuclei have not 

 as yet formed multinucleate masses and many r regulär mitotic figures 

 are still seen. This formation of multinucleate masses or »nests« 

 has been noted by diffenent observers, Carriere and Bürger (11), 

 Heider (23), Schwartze (51) and others. These, in the early phases 

 of mitosis, appear similar to those we have described, but we note 

 that often when division is completed, the resultant nuclei and their 

 membranes formed, the two nuclei are still joined by the connecting 

 fibres. The fibres have already been described as very pronounced, 

 but we here find what we have previously not observed, a persis- 

 tence of the fibres after completed division. Another egg having the 

 appearance of being in nearly the same stage of development, having, 

 however, the cells at the ends of the egg formed and partly rounded, 

 failed to show any yolk nuclei in mitosis, but they had begin to 

 form multinucleate masses. Amitotic division was seen in this egg. 

 The relative stage of development of these two eggs is hard to 

 determine, . one having been cut longitudinally the other transversely. 



A study of the later stages in the development of Polistes shows 

 a complete absence of mitosis in yolk nuclei, although this form 

 of division can often be seen in the blastoderm cells. Direct division 

 is also rare, appearing to be scarce in any of the late stages, and 

 disappearing when the blastoderm cells have become arranged to 

 show the earliest Suggestion of a germinal band. When the blasto- 

 derm cells are formed, and even just before this, the yolk nuclei 

 begin to arrange themselves into multinucleate bodies so that each 

 mass of cytoplasm will contain from two, to six or eight, nuclei. 



10* 



