640 EISEN. [Vol. XV. 



regard to the quantity of haemoglobin contained in them. In 

 other words, Arnold does not hesitate to consider it as defi- 

 nitely settled that the blood-plates are derived directly from the 

 erythrocytes through " Abschniirung" and " Zerschniirung." 

 Arnold also points out that he has found nuclear fragments 

 in the erythrocytes, which fact would explain their supposed 

 presence in the blood-plates. Objections to this theory of 

 the origin of the blood-plates are made by Lowit, Lavdowsky, 

 Scherer, and Wooldridge, who point to the great difference in 

 chemical composition between the erythrocytes and the blood- 

 plates, — differences in haemoglobin, as well as in staining 

 qualities. 



We now mention those according to whose theories the blood- 

 plates are derived from chemico-mechanical precipitations in 

 the blood. 



Wooldridge is of the opinion that precipitations of fibrinogen 

 are not to be distinguished from blood-plates ; thus assigning 

 to the latter a chemico-mechanical origin. 



Lowit, who has entered into this discussion with much skill 

 and energy, tries to demonstrate that the blood-plates are not 

 preformed in the blood, but that they are partly precipitated 

 from the blood plasma and are partly the debris of leucocytes. 



From the above short review it will be seen how different 

 are the views held by the various investigators, hardly any two 

 exactly agreeing as to the origin and nature of the blood-plates. 

 As to the functions of the blood-plates, I believe that most 

 investigators agree that the plates stand in some relationship to 

 the coagulation of the blood. While Bizzozero holds that they 

 furnish the fibrin for coagulation, others, like Ebert and Schim- 

 melbush, contend that they do not form any fibrin but simply 

 conglutinations. 



Though many investigators have studied the blood-plates, 

 few have finally agreed upon any points pertaining to their 

 origin, while their structure has hardly been the object of 

 serious research. The summary of our knowledge of the func- 

 tion and origin of the blood-plates is, I think, most clearly 

 contained in the words of Friedenthal {Biol. Centralblatt, Bd. 

 xvii, No. 19 (October, 1897), p. 713) : It is with certainty 



