312 ALWIN M. PAPPENHEIMER 



So far, only the changes occurring in cells of the small type 

 have been considered. But there takes place also a definite out- 

 growth of cells which differ widely from the lymphoid elements 

 and cannot be confused with them. The first evidence of growth 

 is the projection of delicate protoplasmic sprouts from the mar- 

 gin of the main fragment. These have been seen as early as 

 six hours after the preparation of the culture, but they may not 

 appear until the following day, and rarely the first sign of growth 

 is not seen until the second day. Following the appearance of 

 the sprouts, large cells wander out into the medium, either as 

 isolated cells or as coherent tissue-like planes of compact cells. 

 Often these cells take on an elongated spindle shape and arrange 

 themselves in long rows joined end to end, following a fibrin 

 thread or the line of retraction of the plasma. When the cells 

 grow out along the cover-glass, they become flattened, irregularly 

 pyramidal or oval in shape, with long dendritic, barely visible 

 plasmatic processes uniting them to the central fragment or to 

 each other. The individual cells, as seen by the figure (fig. 7) 

 are often of extremely large size, but are so irregular in shape 

 that it is difficult to give measurements of value. The nucleus 

 is relatively large, elliptical, though sometimes indented by large 

 fat droplets in the cytoplasm. It is usually possible to distin- 

 guish one or two slightly more refractile nucleoli; otherwise, the 

 nuclear substance appears homogeneous. 



From their first appearance these cells are found to be filled 

 with numerous granulae. At first, these are of small and uni- 

 form size, and but moderately refractile; after several days of 

 incubation, the cells contain in addition, many droplets of vary- 

 ing size, which are refractile and evidently fat droplets. The 

 smaller droplets or granulae often range themselves in rows of 

 considerable length. The cell processes are relatively free from 

 granulae, but occasionally do contain small granules, or larger 

 fat droplets. One frequently sees knob-hke thickenings along 

 the coarse of a long plasmatic process in which such granules are 

 found. Where the prolongation of the cell ends blindly, the 

 termination is frayed into delicate hair-like processes, which 

 because of their slight refractivity. appear to shade off into the 

 plasma. 



