NUCLEATED RED CELLS 127 



experiments it became apparent that these bodies were 

 associated with those cells. We have never succeeded, 

 however, in making a platelet reproduce itself, even with 

 the most powerful exciter of cell-division. Blood-plate- 

 lets frequently become clumped into masses, especially 

 if the jelly contains an extract of a tissue; we therefore 

 think that this clumping may have some function in the 

 phenomenon of healing. 



At this juncture it may be useful to dispose of an 

 old theory, that the blood-platelet is the "extruded 

 nucleus" of a red cell. In the first place, no diffusion- 

 vacuoles have ever been seen within the nucleus of any 

 cell, and the platelets, therefore, can hardly be nuclei. 

 This suggestion of the nuclear origin of the platelet 

 would never have occurred, I think, if the originators 

 of it had used in-vitro staining. Red cells are never 

 seen to extrude their nuclei by this method as they 

 sometimes seem to be in the act of doing when they 

 are spread out and fixed on a slide by the old methods- 

 It is difficult to imagine that any cell could extrude its 

 nucleus bodily, and a glance at the stained nucleus of 

 an unfixed nucleated red cell will dismiss such a fallacy 

 in very short time. The nucleus of a living red cell 

 seems to consist merely of a mass of chromatin granules, 

 which appear to be identical with those of the "red 

 cell with basic granules." The granules ultimately 

 seem to disappear altogether, for in normal blood one 

 sees about 1 per cent, of these granular cells, which 

 sometimes have only one or two granules, whereas in 

 anaemia the number of granules is much greater in 

 most of the cells. Presumably, when the granules 



