GIANT-CELLS OF BONE-MARROW 131 



SUMMARY 



1. The hemogenic giant-cells of the red bone-marrow, the 

 so-called megakaryocytes, contain abundant granular and a few 

 bacillary mitochondria. In the earlier stages the bacillary forms 

 predominate, in the later stages the granular are in excess. 



2. The same cells contain also a relatively small Golgi appa- 

 ratus in the form of a more or less complicated skein localized 

 in the vicinity of the centrosomes. The Golgi apparatus frag- 

 ments and disappears in the later multinucleated stages of these 

 cells. 



3. Both of these structures can be demonstrated in the same 

 cells after prolonged treatment with a 2 per cent solution of 

 osmic acid. 



4. The Golgi apparatus thus demonstrated is an entirely 

 different structure from the canalicular network or tropho- 

 spongium first described by Retzius in these cells fixed with either 

 Rabl's or Carnoy's solutions. 



5. The results of this cytologic investigation of these giant- 

 cells in the red bone-marrow of the rabbit and the guinea-pig 

 lead to the tentative conclusions that the so-called tropho- 

 spongium of these cells as demonstrable in Carnoy-fixed tissue 

 is an artifact, that the Golgi network consists of anastomosing 

 varicose fibrils and rods, and that the Golgi apparatus and 

 mitochondria are only morphologically different portions of 

 the same substance, the former resulting from a fusion of the 

 latter while aggregated in the neighborhood of the centrosphere. 



