CHICKEN BONE MARROW IN PLASMA MEDIUM 105 



Proof could only be obtained by cultivating isolated cells of a 

 certain known type in a medium which does not contain fibrin 

 as the plasma does. This has never been done and still re- 

 mains a subject for future investigation. 



The author agrees with Foot's view of 1912, that X cells, or 

 the conspicuous cells in tissue cultures of bone marrow, are of 

 mesenchymal type, not because they contain fibrils, but be- 

 cause their origin could be traced and their cytological changes 

 could be recorded. Foot's statement of 1913, must be refuted: 

 that the transformation passed through the stages of small mi- 

 crolymphocyte, macrolymphocytes, large mononuclear forms, 

 myelocytes, polymorphonuclear eosinophil leucocytes, X cells, 

 cell culture type, omitting one or the other forms of this stage, 

 so that directly a lymphocytic origin is considered. It was never 

 observed that true microlymphocytes were transformed into 

 macrolymphocytes in the tissue culture. The basophil cell with 

 vesicular nucleus, pale cytoplasm of various sizes in the net- 

 work of bone marrow, assumed the cell culture type, after wander- 

 ing into the cytoplasm, forming point-like projections, dis- 

 playing the capability of phagocytosis, storing fat, and being 

 vacuolized. There was no stage observed in this transformation 

 which resembled the large mononuclear lymphocyte or the 'lym- 

 phocytoid Wanderzelle' of Dantschakoff, though this type could 

 be easily observed in chicken bone marrow when the bird had 

 cyanolophia. The close resemblance with Dantschakoff's 'his- 

 tiotype Wanderzelle' — cells which form ('09, page 177), after 

 some changes, the 'ruhenden' wandering cells of the connective 

 tissue — could, only be discovered when the basophil forms left 

 the net-work and began to emigrate. 



It appears highly plausible that in tissue culture the indifferent 

 mesenchymelike cell in the bone marrow network does not show 

 its supposed duality, either to form the known elements of the 

 connective tissue or according to the views of the monophyletic 

 school, the different elements of the hemato- and granulopoesis. 

 In a medium, where circulation has ceased, where no oxygen 

 renovation takes place, the potency to form the lymphocytic 

 elements of bone marrow may not be strong enough to over- 



