120 H. E. JORDAN 



may be termed a polykaryocyte (Jordan, '20). The osteolytic 

 giant-cells, on the contrary, arise by the fusion of originally 

 discrete cells of the bone-marrow, including osteoblasts and 

 reticular cells, and are accordingly always and only multinu- 

 cleated. After Wright's technic, the hemogenic giant-cell, 

 whether mono-, polymorpho-, or multinucleated, and even in the 

 condition of the ancestral hemoblast, is seen to contain a granular 

 endoplasm which takes on a reddish lilac (red to purple) color. 

 The granules are variously designated as metachromatic and 

 azurophil granules. From this granular cytoplasm, by segmen- 

 tation of pseudopods and by fragmentation of larger areas, are 

 formed the platelets. The cytoplasm of the osteolytic giant- 

 cell does not react in this same way to Wright's technic, nor 

 does it produce platelets (Jordan, '18). Furthermore, the 

 hemogenic giant-cells are not phagocytic. The occasional 

 inclusion of erythrocytes must be interpreted as the result of an 

 intracellular differentiation in these potential erythroblasts, 

 comparable to blood islands, and the included granulocytes as 

 the result of an invasion of the disintegrating giant-cell cyto- 

 plasm (Jordan, '20). The chief function of the hemogenic 

 giant-cells is the production of platelets. The osteolytic giant- 

 cells, on the contrary, are distinctly phagocytic. They ingest 

 bone, senile erythrocytes, effete osteoblasts, bone cells, and 

 various other types of debris. 



MITOCHONDRIA 



The giant-cells here to be considered are accordingly only of 

 the hemogenic type, that is, the platelet-forming variety. 



An effort was originally made to stain the mitochondria of the 

 giant-cells in fresh preparations of marrow with janus green. 

 Various dilutions were employed, including the standard one of 

 1 part of the stain to 10,000 parts of a normal salt solution. In 

 such preparations the endoplasm appears granular, the minute 

 granules staining a pale green color. The green-staining granules 

 are presumably mitochondria, but originally such interpreta- 

 tion seemed not quite certain for three chief reasons: 1) the 



