No. 3-] BLOOD-PLATES OF THE HUMAN BLOOD. 645 



ical precipitations of globulin and fibrin. In the blood of the 

 lower vertebrates the fusiform corpuscles have been confounded 

 with plasmocytes or true blood-plates, while the latter have been 

 overlooked. As true blood-plates or plasmocytes, we must con- 

 sider only those structures possessing a definite, finer, inner 

 organization ; those in which may be distinguished outer 

 spheres forming a cytosome, and inner spheres containing cen- 

 trosomes, as well as highly refractive secreted or food granules. 

 Such blood-plates are true plasmocytes, partaking of the same 

 origin as the plasmocytes of Batrachoseps, having budded off 

 from fusiform corpuscles or from nucleated red blood-cells. 



Among the false blood-plates we must distinguish between 

 those which are caused by morphological degeneration and those 

 caused by chemical precipitation. Among the former we must 

 place the fusiform corpuscles which give birth to the plas- 

 mocytes ; in the latter class must be included the disintegrating 

 parts of leucocytes, erythrocytes, and nuclei, which are found, 

 respectively, in the blood of the lower as well as in that of the 

 higher vertebrates, including man. Another class of false 

 blood-plates are those caused by purely mechanical and chem- 

 ical decomposition — precipitations of fibrin and globulin, bodies 

 amorphous as regards shape and without morphological struc- 

 ture. This multiple nature of what has been described as 

 blood-plates has been fully recognized by Friedenthal and 

 Arnold, who both agree that the blood-plates have no unity of 

 origin, but originate by budding and disintegration of red and 

 white corpuscles, as well as from precipitations of fibrin. This 

 assumption is due to a misunderstanding as to the structure of 

 the blood-plates, and cannot be accepted as final. On the con- 

 trary, it shows that there must be a distinction made between 

 true and false blood-plates, between blood-plates and debris, 

 between organized and unorganized blood-plates. A diagram- 

 matic view of this would be as follows : 



