536 



PHYSIOLOGY 



CHAP. 



intermediate between the two. The leucocytic origin of the giant 

 cells is nowadays admitted by every one, although the process by 

 which the one form of cell passes into the other is still unknown. 



The erythrocytes, or nucleated red corpuscles, were described 

 in 1868 by Bizzozero and Neumann, who recognised that they 



Fin. 254. Erythroblasts and erythrocytes from bone marrow of dog, dry preparation. , l>, c, 

 Erythroblasts with more or less developed and excentric nucleus ; d, erythroblasts in mitotic 

 division ; e, f, erythrocytes apparently destitute of nucleus. 



contained haemoglobin. Among them may be distinguished 

 young forms, adults, and those undergoing mitotic division. They 

 can easily be differentiated from the lymphocytes of the same size, 

 not only by the haemoglobin which they contain, but also by the 



FIG. 255. Preparation of human bone marrow, showing the various migratory cells, implanted in 

 the lacunae of an adenoid tissue, leaving large irregular spaces here and there, which are 

 occupied by adipose tissue. (B<">hm and v. Davidott'.) 



different reaction of their cytoplasm to certain stains. Erythro- 

 blasts never in their different stages of development present any 

 cytoplasmic granulation, such as stains with indulin (Trambusti). 

 In their constitution as in their size, the erythroblasts exactly 

 resemble the apparently non-nucleated erythrocytes of the blood, 

 which are found mingled with the nucleated cells of bone marrow. 



