178 



Wm. S. Marshall, 



nuclei appear and little further down larger cells (oöcytes) in whose 

 nuclei the chromatin is massed in an excentric ball. He believes 

 that synapsis has something to do with division but found no dividing 

 cells. Other cells at this region have the chromatin separated into 

 two parts. The oöcytes grow; at first lying two or three together, 

 they later, separate. They now lie in the median part of the tubule 

 with their long axis across it. Cell boundaries which have disappe- 

 ared now appear again. The nucleus of the nurse- cells becomes 

 larger and oval in form, the chromatin finely divided and one or 

 two nucleoli are present. The oöcytes move further apart and the 

 nurse-cells which were arranged in rows, get in between them and 

 begin the Chamber formation. The oöcytes may either appear along 

 the margin or in the central part of the tubule. After the synapsis 

 zone the epithelial nuclei appear, at first pointed, but later becoming 

 rounder. In these nuclei one or two nucleoli are often present, and, 

 at the begining of the Chamber formation cell boundaries are formed. 

 He distinguishes a zone of Chamber formation. He found the opening 

 between nurse and egg Chamber and the process the oöcyte sends up 

 between the nurse-cells. At the beginning of Chamber formation the 

 nurse- cell nucleus has a nucleolus and a finely granulär mass which 

 later becomes thicker. Nuclei become irregulär and secretor}'' activity 

 begins. At this same time the oöcyte nucleus looses the characteristic 

 thread structure it earlier had and the chromatin forms in masses in 

 its central part. It now has a number of the small uuclear-like 

 bodies near it. It looses its regulär form. The nurse cells are finally 

 emptied into the egg Chamber. 



He holds with Korschelt (18) that in the Hymenoptera all three 

 kinds of cells come from similar Clements of the terminal Chamber. 

 In and near the synapsis zone a multiplicatiou of cells begins, they 

 become differentiated and the oöcytes are first recognized as such. 

 He did not see mitosis in the synapsis zone, nor could he find a 

 nucleolus present. In this zone he believes but few mitotic divisions 

 are present and these only for the origin of the oöcyte, the nurse- 

 cells originating amitotically. We will not go further into his 

 theoretical part except to give his origin of the different cells in 

 w^hich he agrees with Koeschelt. The first differentiation comes in 

 the terminal filament and separates the vegetative (epithelial) from 

 the generative cells. A second differentiation later takes place in 

 which the »Keimzelle« become separated into oöcytes and nurse 

 cells. 



