CHICKEN BONE MARROW IN PLASMA MEDIUM 93 



But together with these retrograde processes, easily observed 

 in the Uving culture, small parts of the irregularly-shaped, large, 

 disintegi-ating fat cells isolate themselves. They become spheri- 

 cal in shape and begin to wander away from their 'mother cells.' 

 They can be recognized by their small nuclei, their coarse glisten- 

 ing plasma. They are identical with small fat cells. This 're- 

 juvenation' of the fat cell was only observed when bone marrow 

 tissue of younger well-fed animals was implanted. Bone marrow 

 from very young chickens and tissue from old hens seldom re- 

 juvenate the fat cells, when such are present. In tissue from 

 older hens the disintegration of the fat cells often obscures the 

 observation of the other cell types. 



THE FATE OF THE MONONUCLEAR BASOPHIL CELLS OF THE BONE 

 MARROW IN TISSUE CULTURES 



\\'Tien implanted in the plasma medium, the bone-marrow 

 particle itself appears basophil after preservation with Orth's 

 fluid and staining with Giemsa stain. For a long period, up to 

 14 days, it shows a strong basophilic character. We have shown 

 how fat cells and their derivatives generally have a strongly 

 basophil nucleus and often a basophil plasma. Erythrocytes, 

 erythroblasts, and eosinophil leucocytes, which show a strong 

 basophily of the nucleus, emigrate or are washed out of the tis- 

 sue particle and either perish or undergo the changes described. 

 The eosinophil leucocytes, diminishing the size of their nuclei 

 and acquiring an acidophil cytoplasm, later form, together with 

 the erythrocytes, the reddish halo around the implanted particle. 



After the first emigration or washing out of the cell types 

 mentioned, the tissue particle consists almost solely of basophil 

 cells, which are very young, small, unripe erythroblasts, small 

 lymphocytes, connective tissue cells of the bone marrow net- 

 work, and basophil cells of all sizes and forms, the character of 

 which is not at first recognizable. The thickness of the tissue 

 particle prevents the closest examination, but these cells have 

 always ungranulated plasma. In figure 8, a general survey of 

 these basophil cells is given, as they appear after one hour's in- 



