Zool.— Vol. I.] EISEN—PLASMOCYTES. 21 



increase in size together, and in such a way that the largest 

 plasmocytoblasts are always those which inclose centro- 

 somes and centrospheres. The plasmosphere appears 

 fringed, partly from actually being so, partly, also, on ac- 

 count of a row of dots of dark-staining cytoplasm arranged 

 along- the edge. These dots never occur in a continuous 

 line, but run in a zigzag way near the edge. The arrange- 

 ment of these fringed or plasma-projections is like that of 

 the radii in a circle or the rays of a star. The plasmosphere 

 sometimes gives the impression of being at rest, as rep- 

 resented by figs. 21, 27, 34, and others. At other times 

 it appears to have become fixed while in amoeboid activity, 

 as seen in figs. 25^, 29*7, 32$, 33^, etc. While MacCallum 

 noted the frayed appearance of the plasmosphere and figured 

 it, his method of staining could not bring out any of the de- 

 tails of differentiation, though some of his figures slightly 

 indicate that he had observed some structures corresponding 

 to the inner spheres. 



I have already pointed out that in a few plasmocytes I 

 observed a membrane surrounding the plasmosphere, caus- 

 ing the corpuscle to look very much like a real cell. In the 

 plasmocytoblast no such membrane has ever been observed, 

 as all possess a more or less fringed plasmosphere. While 

 in the resting stage the plasmosphere presents an out- 

 line of rounded protuberances, which may be either very 

 small and even, as in fig. 21, or they may be large and un- 

 equal in size, as in fig. 27. When properly stained the 

 cytoplasmic accumulation at the edges is always prominent, 

 and we find it either in the shape of more or less regular 

 globules, or as wedges tapering towards the hyalosphere. 

 The toluidine is the only stain which brings out this cytoplas- 

 mic arrangement, and even a counter stain will prevent them 

 from being observed. These small cytoplasmic masses 

 seldom extend beyond the sharp line of the hyalosphere, 

 and only once did I find them so irregularly scattered that 

 the hyalosphere was obscured, as in fig. 38^. 



The question arises as to whether the fringed appearance 

 depends upon amoeboid movements or not. As I will return 



Proc. Cal. Acad. Sci., 3D Ser., Zool., Vol. I. (2) Oct. 20, 1896. 



