64 KANSAS UNIVERSITY QUARTERLY. 



Synchronously with these changes in the character of the nucleus, 

 the cell has undergone a truly remarkable increase in size. In the 

 early spireme stage the average diameter of the cell was about ten 

 micra ; now the average diameter is thirty-five micra, and the largest 

 cells reach an enormous size, their diameter being about ninety micra. 

 By this extensive growth the cytoplasm has increased in amount much 

 more than has the nucleus (fig. 4), but still shows its finely reticular 

 structure. Embedded in the meshes of this network are large masses 

 of yolk material. This food substance generally forms a zone sur- 

 rounding the nucleus, the inner portion being but little denser than 

 the cytoplasm, while the outer portion, which is often broken up into 

 uneven projections, stains much more densely. Occasionally the 

 deutoplasm is not arranged in the manner described, but is distributed 

 irregularly around the nucleus in masses of various sizes. At this 

 stage I have been unable to find any centrosome or attraction sphere. 



As will be seen from the plates, the spermatocyte, during this dif 

 fuse reticular stage, approaches very nearly the egg type. Indeed, 

 this similarity is so striking, that upon a superficial examination, I 

 was inclined to believe that these cells were really egg-cells, and, as 

 various stages of the male germ-cells were also present, that the ani- 

 mal, contrary to general belief, was hermaphrodite. However, upon 

 further study, this first impression was soon found to be erroneous, as 

 the true character of the cells was then conclusively apparent. 



So far as I have been able to learn, male cells so very similar to the 

 egg-cells have never been described. For that stage of the prophase 

 in the spermatocytes of Scolopendra I wish to propose the name of 

 the pseudo-germinal-vesicle stage. At this time the nucleus is, in ap- 

 pearance, identical with the typical germinal vesicle of the egg. It is 

 small in proportion to the amount of cytoplasm, and is situated some- 

 what eccentrically. The reticulum is very similar in appearance to 

 that of the immature ovum, and the accessory chromosome resembles 

 very closely the germinal spot of the female element. Indeed, the 

 later behavior of the accessory chromosome is very much like that of 

 the germinal spot in those eggs in which the chromosomes are derived 

 from this element. 



From the diffuse germinal vesicle stage described, the chromatin 

 reappears as a number of diffuse masses. These quickly assume a 

 form identical with that of the typical insect tetrad, described by 

 Paulmier^ in Anasa, and by McClung^ in Jlippiseus. The process 

 of the formation of these tetrads is so rapid that they often appear to 

 arise from the diffuse pseudo-germinal-vesicle stage as well-defined 



3. Paulmier, F. C. 1899 : "The Spermatogenesis of Anasa tristis," Jour. Morph., vol. XV. Sup- 

 plement. 



4. McCluDg, C. E., 1900, loc. cit. 



