No. 3] BLOOD-PLATES OF THE HUMAN BLOOD. 64 1 



established through observations under the microscope, that 

 fibrin threads always radiate from heaps of blood-plates ; but 

 whether the latter originate from the red or from the white 

 corpuscles of the blood cannot be decided. 



In conclusion, I will only state that, according to my own 

 views, the true blood-plates are neither derived from budding 

 erythrocytes, nor from leucocytes, but that they constitute the 

 archosomes — -centrosomes with spheres — of erythroblasts or 

 of other nucleated cells, which archosomes have separated 

 themselves from their attachment to the nuclei in the same 

 manner as the plasmocytes of the batrachian blood separate 

 themselves from the fusiform corpuscles. 



IV. Blood-Plates, Plasmocytes, and Fusiform 

 Corpuscles. 



As has been mentioned, Bizzozero, Casimiro Mondino, Luigi 

 Sala, and others compare the blood-plates in the human blood 

 to the fusiform corpuscles of some of the cold-blooded verte- 

 brates. Between these respective elements there is, however, a 

 very great difference, both as regards size and structure. The 

 blood-plates in the human blood are many times smaller than the 

 red corpuscles, while the fusiform corpuscles are always of very 

 nearly the same size as the red corpuscles of the same blood. 

 As regards structure, again, we find that the fusiform corpuscles 

 are each characterized by a more or less perfect nucleus, while 

 it can be shown that in the blood-plates no such nucleus exists. 

 The only similarity between the blood-plates and the fusiform 

 corpuscles is that the nature of each causes them to adhere 

 together and to other objects through the aid of peculiar 

 fringed filaments ; thus causing them to form masses of lesser 

 or greater extent. 



In the great majority of cold-blooded animals no blood ele- 

 ments are found which can be compared to the blood-plates in 

 the human blood. In the small batrachian, Batrachoseps atte- 

 nuatus, I have, however, recently described minute bodies, 

 exteriorly, which somewhat resemble fusiform corpuscles, but 

 are of smaller size and of a different structure, there being no 



