1909.] The Vacuolation of the Blood-platelets. 



353 



the coefficient more than any substance that has been tried as yet, and it 

 appears to have a greater effect on the cytoplasm than other poisons. As all 

 the platelets in a specimen usually become vacuolated, I believe that they all 

 belong to one class of cell, derived from one source. 



In view of the vacuolation, the precipitate theory of the blood-platelets 

 becomes untenable. Another theory, that they are the extruded nuclei of 

 red cells, can also, I think, be dimissed. Torruer researches have shown that 

 the nucleus of a cell is its " higher centre." It is difficult to believe that a 

 cell can thrust out its nucleus. Moreover, in the paper in ' The Journal of 

 Physiology,' already referred to, it was stated that the spots in leucocytes 

 were never seen to be connected with the nucleus. The platelets, therefore, 

 can hardly be nuclei. The nuclear theory is, I believe, the outcome of the 

 examination of dead structures. Blood-platelets are never seen emerging 

 from red-cells when in vitro methods are employed. 



I believe that the theory that the blood-platelets are fragments of 

 leucocytes is the correct one ; they have the same coefficient of diffusion as 

 those cells, and usually contain a few granules which have the same staining 

 rate as those of the leucocytes. When blood is placed on jelly which excites 

 amoeboid movement in leucocytes,* the platelets have been seen to extrude 

 and retract pseudopodia. On a few occasions, a pseudopodium has been seen 

 to become separated, and the fragment appears to be identical with the 

 other platelets seen in the specimen. It may contain clear cytoplasm, a few 

 granules, or even a lobe of the nucleus. 



* 'The Lancet,' January 16, 1909. 



