WENRICH: spermatogenesis of PHRYNOTETTIX MAGNUS. 73 



point, for there still can be seen the remnants of the vesicular walls 

 which surrounded each chromosome in the earlier telophase. 



There are 21 of these chromatin-masses, or "blocs" (Janssens, '01), 

 shown in this optical section, and that is sufficiently close to the total 

 number, 23, to indicate that all the chromosomes are still independent, 

 except for the union at the polar ends, as already mentioned. 



In figure 21 it will be noticed that the diffusing chromatin is dis- 

 posed roughly in the form of spirals. Figures 23 to 29 indicate what 

 becomes of these spirals in the " blocs" of chromatin. I am not quite 

 sure of the exact succession of stages here, but believe they are about 

 as shown in the successive figures. It is possible that figures 23 and 

 24 — which are side view and optical section, respectively, of the same 

 stage — are no earlier than the stages shown in figure 25 (Plate 3). 

 However that may be, the evidence seems to indicate that each of the 

 blocs at stages such as those shown in figures 21 and 22 gives rise to a 

 single fine thread, at first much coiled but later much elongated. 



The side view shown in figure 23 is at a stage the casual examination 

 of which might lead one to suppose that the chromatin was in a hope- 

 less tangle without any definite arrangement whatever. But careful 

 focussing and patient study revealed what I have tried to show in 

 figure 23, viz., that the chromatin is still disposed, for the most part, 

 in separate blocs, but that a very much coiled and convoluted thread 

 is forming within each one of these territories. Some have unraveled 

 to a considerable extent, and have become extended in various direc- 

 tions through the nuclear sap. But each seems to be a continuous 

 thread, despite some tendency for the ragged edges at times to be 

 connected with adjacent threads. In the optical section of this stage 

 (fig. 24) it will be seen that the blocs have remained in place and 

 separate from each other for the most part, though some anastomosis 

 of the linin fibers has taken place at the periphery of the blocs. On the 

 other hand, there are still some remnants of the previously existing 

 vesicular walls, as shown in the left side of the figure. When one 

 focusses up and down on such a cell, it is possible to follow in some cases 

 the tliread which is differentiating out of the net-like structure of each 

 bloc, but in optical section the reticulum is more apparent than the 

 continuous thread. The section shows nineteen blocs, which number 

 is not far from the somatic number of chromosomes (23). Figures 

 23 and 24 represent what I have called the preleptotene stage. 



At the stage shown in figure 25 (Plate 3), which I believe to be 

 slightly more advanced than the one in figures 23 and 24, the amount 

 of anastomosis between adjacent chromatic elements seems consid- 



