9 o 



CHILD. 



[VOL. I. 



spicuous condensation of the cytoplasm. As stated above, the 

 cytoplasmic network of these cells is in general quite coarse. 

 This statement, however, does not apply to the sphere. Al- 

 though I have not seen the stages of the formation of the 

 sphere, I believe from its appearance and relation to other 

 parts of the cell that it is without doubt simply a condensation 

 of the cytoplasm. In the figures it is represented as granular, 

 but this appearance is probably due to the condensation. In 

 staining qualities it resembles the cytoplasm, except that it 

 takes the plasma stains much more deeply, and thus stands out 

 very distinctly from the rest of the cytoplasm. Radiating fibers 



FIG. 2. 



FIG. 3. 



like those so common in astrospheres and spindles in the vari- 

 ous stages of karyokinesis are not present, but the sphere 

 resembles very closely the structure described by Auerbach ('96d) 

 as "Nebenkern" in the spermatogonia and spermatocytes of 

 Paludina, and, I believe, arises in the same way. But, though 

 no distinct fibers are visible, the structure of the cytoplasm 

 around the sphere proper is more or less distinctly radiate. 

 Two of the cells in Fig. I show this to some extent, as does 

 also Fig. 2. Sometimes this radiate arrangement is visible, 

 though indistinctly, nearly to the periphery of the cell, as I 

 have attempted to show in Fig. 3. It is probable that the dif- 

 ference between a sphere of this sort and a distinctly radiate 

 sphere with fibers is one of degree and not of kind. 



Perhaps even more striking than the presence of this sphere 



in these cells is the presence of a perfectly distinct centrosome 



- or in some cases two - - in its center. Two of the cells in 



Fig. i show two centrosomes, the rest in which the sphere is in 



the plane of section show one. 



