Zool— Vol. I.] RISEN— PLASMOCYTES. 59 



2. The vast majority of the erythrocytes are not nu- 

 cleated, hardly any being found in the spring of the year. 

 In the summer and autumn they are more numerous than at 

 any other time. In this, also, Batrachoseps stands alone; 

 all other batrachians possessing only nucleated red blood 

 cells, at least according to our present knowledge. 



3. A perfect nucleated erythrocyte of the blood of 

 Batrachoseps consists of three distinct and separately or- 

 ganized parts, which, however, are not of equal importance 

 in the general make-up of the cell. These parts are the 

 Cytosome, consisting of three cytoplasmic spheres — plas- 

 mosphere, hyalosphere, and granosphere; the Archosome, 

 consisting of three archoplasmic spheres — centrosphere, 

 somosphere, and centrosomes; and the Caryosome, or 

 nucleus. 



4. The observed facts further verify the theory that the 

 fusiform corpuscles are the remains of nucleated erythro- 

 cytes which for some reason have lost their cell wall and 

 haemoglobin. This fusiform corpuscle is thus newly 

 ejected nucleus to which is yet attached most of the cyto- 

 plasm of the cell. 



5. At and after the separation of the fusiform element 

 from the rest of the cell the archosome remains in the fusi- 

 form element until the plasmocyte is formed. 



6. The origin of the fusiform corpuscle is due to a de- 

 fect in the nucleus, or more particularly in the chromo- 

 somes. This defect has prevented the chromosomes from 

 assuming the preliminary skein stage preparatory to divis- 

 ion. The archosome, which has already entered upon the 

 second stage of mitosis, having divided and moved to oppo- 

 site poles, cannot, therefore, conclude the process, the 

 energy expended effecting only the rupture of the cell mem- 

 brane, thus setting free the fusiform element. 



7. The fusiform corpuscle consists of the nucleus and 

 one or two plasmocytoblasts, 1 each one of which consists 

 of six cytoplasmic zones, including centrosomes. 



1 In the foregoing, and throughout this paper, I have used the word plasmocyto- 

 blast in order that I may be clearly understood; but for the sake of brevity I propose 

 that this word be made simply plasmoblast. 



