Zool.— Vol. I.] EISEN—PLASMOCYTES. 37 



ference in size. It is generally the larger sphere which 

 stains the most intensely, and this unequal differentiation 

 may be due either to disintegration and decay or to poor 

 nourishment. It appears as though some of the spheres are 

 stronger and better able to procure nourishment than others. 



General Absence of a Cell Membrane. — That the plasmo- 

 cytes are not generally surrounded by any cell membrane has 

 already been stated. The exterior layers show projecting 

 plasmarays entirely without any membranous covering. 

 This might be expected on account of the origin of the 

 plasmocyte from a part of the cell which had lost its cell 

 membrane; but out of the very many plasmocytes inves- 

 tigated I have found some, not more than half a dozen 

 in all, which, as far as concerns their exterior margin and 

 form, present a very different appearance. These plasmo- 

 cytes, if such they are, present a rounded form with smooth 

 outline covered by a distinct cell membrane ; but, unlike 

 most plasmocytes, I could never see in them any differ- 

 entiation between the plasmosphere and the hyalosphere, 

 and even the outline of the granosphere was less well de- 

 fined. I believe, however, that these bodies are real plasmo- 

 cytes, though as to the cause of their structure I can venture 

 no opinion. In fig. 59 I have represented one of them. Be- 

 sides these plasmocytes I have also found in the blood very 

 much smaller bodies, appearing like very small isolated 

 nuclei without cytoplasm. My investigations of these are 

 as yet unsatisfactory. 



Absence of Nucleus. — The absence of any nuclear struc- 

 ture in the plasmocyte is readily explained by the well 

 known law that the cell originates only from the cell, and 

 the nucleus only from a previous nucleus. In one or 

 two instances, however, I have found a structure near 

 the center of the plasmocyte which might perhaps be called 

 an incipient nucleus, an effort to form a new nucleus of 

 some existing nuclear fragments which may have en- 

 tered the plasmocyte. In fig. 75 such a pseudonucleus 

 is seen, as it were, in mitosis (see also fig. 74). Such 

 forms are, however, exceedingly rare, and these two are 



Proc. Cal. Acad. Sci., 3D Ser., Zool., Vol. I. (3) Oct. 21, 1896. 



