Zool.— Vol. I.] EISEN— PLASMOCYTES. 3 1 



mocytoblasts, viz.: those which are ready to separate them- 

 selves from the fusiform corpuscles. Whether stained one 

 way or the other, I find that the respective spheres behave 

 in the same way, and that those of the plasmocyte are al- 

 most exact copies of those of the plasmocytoblast. From 

 the youngest plasmocytoblast to the oldest plasmocyte it is 

 not difficult to arrange a perfect series of forms showing a 

 gradual gradation of one into another. An examination of 

 figs. 40 to 84 will demonstrate this better. 



Different Kinds of Plasmocytes. — While all plasmocytes 

 possess a number of characters in common, they still differ 

 in some degree, sufficiently to be worthy of description. 

 For convenience sake we can segregate them into groups, 

 according as we find in them one, two, three, or possibly 

 four separated spheres, side by side, each containing one 

 or more centrosomes; but between these different types 

 there are gradations showing the variations to be of 

 minor importance. As representative of one of these types 

 I will refer to figs. 40, 44, 47, 49, 55, 60, etc., taken at 

 random. The common character of these six corpuscles is 

 that of the centrosome or centrosomes being surrounded by 

 an envelope consisting of all the various spheres described 

 above, concentrically arranged. In another type of plas- 

 mocyte we find that the common envelope contains only 

 two of the spheres, the plasmosphere and the hyalosphere, 

 while there are two or three separate archosomes, each of 

 which has its own separate envelope of granosphere. Such 

 plasmocytes are figured in 68, 69, 70, 71, and 72. Thus 

 the division in the plasmocytoblast has in these not extended 

 to the two other spheres. We have here simply an original 

 plasmocytoblast separated from the nucleus of the fusiform 

 corpuscle and closed up by the two outer spheres before 

 the archosomes separated themselves sufficiently for each 

 one to become the center of a plasmocyte. Still another 

 type is represented by figs. 61, 63, 65, 66, 79, etc., in 

 which we find that the division has not even extended to the 

 granosphere. In these the granosphere is continuous 

 in the same way as the two outer spheres, only the archo- 



