BLACKMAN: THE SPERMATOGENESIS OF SCOLOPENDKA. 9 



deeply by Congo red. In the interstices of this reticular matrix of 

 the testis are contained numerous granules and globules of nutritive 

 material. There are at least two kinds: (1) globules of an oil-like 

 appearance, which in the material fixed in Flomming's mixture are 

 stained in the manner which is characteristic of oil droplets under the 

 action of osmic acid ; (2) numerous irregular masses of a granular con- 

 sistency, which react in a different manner to reagents. This material is 

 not colored by the fixing reagents, but when stained with iron-haema- 

 toxylin and Congo red assumes a brown color. While this interstitial 

 substance is present around all the cells, it is not equally abundant in 

 all regions. At the periphery of the testis, around the spermatogonia, 

 there is not nearly as much as in the deeper layers, in the region of the 

 growing spermatocytes ; and here there is not as much as in the large 

 intercellular spaces enclosing the larger type of vesicles. Surrounding 

 these immense cells there is often quite a thick layer of this nourishing 

 matrix. The cells of the smaller type of spermatocytes are not so well 

 supplied with this food material as the large ones are ; the results of 

 this I shall discuss later, when speaking especially of these cells. There 

 seems to be a greater pressure in the region occupied by these smaller 

 cells, which forces them closer together and thus diminishes the supply 

 of nourishment which they receive. 



Thus the spermatocytes of Scolopendra are supplied during the growth 

 period with large quantities of food material, much more than is usual 

 in the case of the testis cells of other animals. Indeed, the conditions 

 very closely approximate those existing around the egg during the cor- 

 responding stages of its evolution. This is especially marked for the 

 large spermatocytes, — the type which more closely resembles the egg 

 in structure and behavior, — but is also true to a less degree of the 

 smaller type of cells. 



These facts help to explain why the spermatocytes of Scolopendra 

 resemble so closely typical egg cells. The conditions surrounding the 

 cells of the testis are practically identical with those of the ordinary egg. 

 Nourishment is accomplished in a similar manner. The arrangement of 

 the large spermatocytes in the follicle is similar to that of the eggs of 

 many animals. 



From observations given more in detail in the course of this paper, I 

 believe we are justified in concluding that the germ cells of this animal 

 are in a very plastic condition. They are but slightly differentiated and 

 are hence very easily acted upon by environmental influences. Because 

 of a very plentiful supply of nourishment these cells increase greatly in 



