642 EISEJV. [Vol. XV. 



nucleus or chromatin present. As will be shown in this paper, 

 these plasmocytes have almost the identical structure of the 

 human blood-plates and must be considered to be of the same 

 nature. I have also shown that these plasmocytes bud out 

 and separate from the fusiform corpuscles, after which the 

 latter decay and disintegrate. It is but a logical conclusion 

 to suppose that the blood-plates of the human blood must 

 have a similar origin ; that they are derived from nucleated 

 corpuscles or erythroblasts, and possess a complicated, distinct, 

 and invariable structure. The blood-plates cannot possibly be 

 considered as precipitations of globulin, fibrinogen, or of other 

 substances in the blood. On the contrary, we must recognize 

 in them a distinct physiological and morphological element of 

 the blood — an element with a phylogenetic life-history and 

 with important physiological functions. 



V. Life-History of a Plasmocvte. 



As my original paper on the plasmocytes of the batrachian 

 blood may not be accessible to every one interested in this 

 subject, the following short summary of my former researches 

 may be acceptable. In the blood of batrachians, reptiles, 

 and birds there exist corpuscles void of cell membrane, but 

 furnished with a nucleus. These "fusiform corpuscles," as 

 they are generally termed, are nothing but disintegrating nucle- 

 ated red corpuscles, which have lost their haemoglobin as well 

 as their cell membrane. At each opposite pole of this corpuscle 

 is seen at first a very small cytoplasmic projection or bud. In 

 this bud or " plasmocytoblast " we can distinguish the centro- 

 somes of the original red blood-cell, surrounded by several 

 differentiated layers of cytoplasm and archoplasm. This bud 

 grows rapidly, the centrosomes separate from each other, sur- 

 round themselves with cytoplasmic envelops and show otherwise 

 great activity. At last the bud or buds separate themselves 

 entirely from the nucleus of the fusiform corpuscles and become 

 free and independent elements in the blood. These independ- 

 ent elements I have named "plasmocytes." At first they are 

 very small, but they soon grow and reach even the size of small. 



