118 H. E. JORDAN 



finally gave the most satisfactory results was a modification, 

 with respect to time of fixation, of the Kopsch technic. This 

 consists of immersion of very small pieces of the marrow in a 

 2 per cent solution of osmic acid for a period of four weeks. 

 The tissue must be kept in the dark in an air-tight glass-stop- 

 pered vial during the entire period of fixation. This technic 

 reveals both mitochondria and a Golgi apparatus in the same 

 sections and in the same cells. 



GENERAL 



Only two references occur in the literature concerning mito- 

 chondria in medullary giant-cells. Dubreuil ('10) records 

 observations on both the osteoclasts (myeloplaxes of Robin) 

 and what he terms the cells of Bizzozero. The latter are iden- 

 tical with the megakaryocytes of Howell. In tissue fixed with 

 Regaud's potassium bichromate-formol solution and stained with 

 iron hematoxylin, Dubreuil describes a great abundance of 

 minute granular mitochondria in the osteoclasts. The same 

 technic revealed occasional, very minute, deeply staining granules 

 in the megakaryocytes. Dubreuil is only willing to say that 

 these latter granules are probably of the nature of mitochondria. 

 Prenant ('11), presumably using the Benda technic, claims to 

 be able, with considerable difficulty, to demonstrate granular 

 mitochondria of varying abundance in what he terms megakaryo- 

 cytes. He does not state what marrow was used in his investi- 

 gation. Neither Dubreuil nor Prenant give any illustrations in 

 connection with their descriptions. It is therefore uncertain 

 whether these investigators in all cases of cells called 'cells of 

 Bizzozero' and 'megakaryocytes,' respectively, were actually 

 dealing with the hemogenic giant-cells, or that all the polykaryo- 

 cytes were actually osteoclasts. One becomes especially sus- 

 picious in the case of Dubreuil, for he describes osteoclasts as 

 giant-cells with either a single giant nucleus or with multiple 

 nuclei. The cells of Bizzozero, or megakaryocytes, he correctly 

 describes as cells with a nucleus with many buds, that is, cells 

 with a complex or polymorphous nucleus. As a matter of fact, 

 osteoclasts exist only as cells with more than one, usually many 



