80 V. E. EMMEL 



Turning finally to the cells of the third group it will be ob- 

 served that their most distinguishing characteristic is the pres- 

 ence of cytoplasmic vacuoles. The nuclei may be round or flat- 

 tened, are usually more or less eccentric in position and do not 

 differ materially from the nuclei of the phagocytically active 

 macrophags. The vacuoles vary greatly in number and size, 

 so that while in some cases only one or two may be observed, in 

 other instances they are sufficiently numerous to fill almost the 

 entire cell body (figs. 14 vcm. and 13). While many of these 

 vacuoles are filled with an apparently homogeneous material 

 which is non-staining with Giemsa, others contain remnants of 

 hemoglobin and nuclear staining elements. In comparing such 

 cells as figure 5 with its almost entirely digested erythrocytic 

 inclusion, figure 6 and 14 pcm., with large vacuoles containing 

 just a trace of ingested material, and figure 86 in which one of 

 the vacuoles contains a cellular remnant while the two others 

 are practically clear, there can hardly be any question but that 

 many if not the majority of these vacuoles have arisen in con- 

 nection with intracellular digestive processes. Upon the com- 

 plete transformation of the chromatic elements of the ingested 

 erythrocyte there may thus still remain, for a time at least, 

 a non-staining vacuole-like structure in the cytoplasm of the 

 phagocyte. 



In resume it appears, therefore, that the size, form, nuclear 

 and cytoplasmic difference between these three types of cells 

 are to be regarded as correlated with variations in the degree 

 of differentiation and functional activity rather than as indica- 

 tive of differences of a more fundamental character. The most 

 prominent function of these cells being that of phagocytosis, 

 they may not inadequately be designated as the coelomic macro- 

 phags of which the cells of the first type present the least differ- 

 entiated and least active stages and the cells of third type end 

 stages in functional activity. That these coelomic cells are not 

 only manifesting normal functional changes and cytological 

 differentiation but are also undergoing cell multiplication is 

 positively demonstrated by the not infrequent occurrence of 

 mitosis (figs. 3 and 7). Indeed in some instances it appears that 



