STUDIES OF REPRODUCTIVE ELEMENTS : I. » 



zwei runde Körper, die ich vorläuHg al« Micronucleolen bezeichnen 

 möchte." This, as will be seen from my ligures, corresponds exactly 

 with what I have seen in the egg-cells of Diapfomus, the sole differ- 

 ence lying in the absence of the small bodies besides the nucleolus 

 which he calls micronucleoli. These appear, in my case, first in eggs 

 that are nearly ripe, and shortly before tlie formation of the first 

 polar body, as will be seen later on. 



In fig. 24, which represents a part of an ovarian sac, are seen 

 on the right the cells of the formative zone, which towards the left 

 gradually pass over into those of the growing zone. The chromatic 

 elements, as will l^e seen, disappear as we pass from the jjlind end 

 outward, while a distinct nucleolus comes into view. 



The formation of yolk-granules and consequently the rapid 

 development of germ -cells takes place first when the eggs get into 

 the oviduct, just as in the case of Gijclops. As in that case also, all the 

 eo-(y-cells in the oviduct are at a oiven time in one and the same stage 

 of development. Hacchcr says on this point : " die sammtlichen 

 Eizellen des nämlichen Individuums" are found " stets auf fast voll- 

 kommenen gleicher Entwicklungsstufe." 



Of the origin of volk ui'aniiles I liaNc not much to sav. Thev 

 originate, as [ stated of the e^^^^^ of Atye'plilra, in the body of the egg- 

 cell ijear the periphery rather than near the centre. 



The next change in the development of the egg- cells is the a [)- 

 pearance of a number of small bodies in the nucleus, besides the nu- 

 cleolus, which correspond with the " Micronucleolen " of Haecker ; 

 tliere appear at the same time a number of dumb-bell shaped chro- 

 mosomes exactly corresponding with those found in the spermatic 

 cells. The iiucleolus at this time is found to l)e much reduced in size 

 and it shows very often a number of vacuoles of variable sizes. Like 

 HaecliiV I am also ;i1 a loss to know wlu'tlicr tlie iiiio-oniilcoJi arise 



