CHICKEN BONE MARROW IN PLASMA MEDIUM 89 



from fat cells losing their fatty contents and assuming the char- 

 acter of the known type of connective tissue cells. Or the con- 

 nective tissue cells, implanted together with the adipose tissue 

 may have developed and multiplied. This is a separate ques- 

 tion which has not been sufficiently studied in true adipose 

 tissue. 



The changes of the fat cells of bone marrow in tissue culture, 

 though not considered by all authors to be real fat cells, have a 

 great resemblance to phenomena seen in rapidly growing embry- 

 onic adipose tissue, as Foot remarks (p. 48, '12). But he himself, 

 neither in 1912 nor in his later publication of 1913, states the 

 ultimate fate of the implanted, so-called fat cells, which, together* 

 mth the other cells of the bone marrow, are in the culture medium 

 and are numerous in the white bone marrow of the adult chicken. 

 The typical signet-ring cell may apparently remain unchanged for 

 24 hours in the plasma medium, as it is shown on a photograph 

 (fig. 46, right side, above). But the observed facts do not agree 

 in most cases with this view. After three hours incubation all 

 fat cells show still their accustomed shape. The big fat -globule 

 surrounded by a brim of cytoplasm flattens out and the large 

 globule of fat separates into small droplets. Or the fat cell 

 divides into two parts, and even a process of budding may be 

 observed (figs. 29 and 30). If the cell has not divided up, the 

 fat globule diminishes in size and does not fill the whole cell. 

 With a specific fat stain it can be shown that the cytoplasm is 

 filled with small fat droplets and strands (fig. 28). Later foam- 

 like masses of cytoplasm, in the meshes of which the fat is easy 

 to identify, protrude from the cell margin and separate them- 

 selves partially or totally from their 'mother cell.' Cells of 

 this kind may offer the appearance of cells figure in figure 2, 

 left side, in unstained preparations. In a tissue culture of 24 

 hours incubation, preserved with Orth's fluid and stained with 

 Giemsa stain; they appear as cells with highly chromatic nuclei, 

 and perforated cytoplasm (figure 7, right side and figures 33 

 and 34) ; also weblike masses, apparently without nuclei, are 

 frequent (fig. 7) which are often surrounded by microlympho- 

 cytes and polymorphonuclear leucocytes. Text-figure A gives 



