HOFBAUER CELLS. 313 



septicemia, and, until the true nature of such degenerate leucocytes became 

 evident, it was very puzzling to see why the Hofbauer cell, which never was found 

 to contain evidences of phagocytosis when lying in the stroma of a villus, should 

 become phagocytic when contained in a degenerated amniotic or chorionic mem- 

 brane or when lying in a hemorrhagic area. Undoubted instances of phagocytic 

 Hofbauer cells were never seen, although, in addition to those already mentioned, 

 certain misleading forms, as shown in figure 238, were encountered also in pregnant 

 tubes and in an ovarian pregnancy. Among these misleading forms were speci- 

 mens of binucleate cells in which one nucleus had undergone almost complete 

 chromatolysis, leaving only a nuclear membrane. These nuclear remnants or 

 so-called nuclear shadows can easily simulate a phagocytosed erythrocyte. The 

 same is true of small areas of cytoplasm which stain but faintly, and hence look 

 more translucent, and particularly of vacuoles themselves. 



Essick (1915) found what he regarded as morphologically similar cells in 

 transitory cavities in the corpus striatum, and believed them to be macrophages. 

 Consequently, he concluded that Hofbauer cells also are phagocytic and regarded 

 them as having an endothelial origin. I have not been able to find any evidence 

 for the latter origin, however, for in specimens in which the capillaries are plugged 

 with degenerate endothelial cells, or in which they are composed of a layer of 

 greatly enlarged edematous endothelial cells, so as to make the cross-section of the 

 vessels look not unlike that of a duct, Hofbauer cells were never found in close 

 proximity to capillaries or other vessels or in unusual numbers elsewhere in the 

 stroma of such villi. Nor did I see any evidence for such an origin in villi taken 

 from hemorrhagic or inflammatory cases, and although Hofbauer cells often lay 

 near to, or even in extravasations in the villi, they were never found engorged with 

 erythrocytes or pigmented. Nevertheless, if Hofbauer cells arise from mesen- 

 chyme cells, it stands to reason that they at least may be potentially phagocytic, 

 and failure to find them so may be accounted for by the fact that they possess a 

 lowered vitality in consequence of degenerative changes. 



I am prompted to suggest, in connection with the question of phagocytosis, 

 that, unless we regard the process as other than an actively vital movement on 

 the part of the cell for the purpose of engulfing things, we have undoubtedly 

 misused the term. That the mere incorporation of parts of cells, or even of whole 

 cells, within the cytoplasm is not sufficient evidence for the possession of phago- 

 cytic activity on the part of a particular cell, seems to me beyond question. In 

 some instances, for example, degenerating phagocytic leucocytes fuse with each 

 other in groups of twos, threes, or even in greater numbers, thus forming large, 

 multinucleated, and not infrequently vacoulated complexes. Similar phenomena 

 can be seen also among degenerated erythroblasts and trophoblasts and in Hof- 

 bauer cells, as shown in figures 239 and 240. Although it would be incorrect to 

 regard these degenerate fusion products as true, living giant-cells, they neverthe- 

 less simulate such very closely indeed. Moreover, when these larger fusion prod- 

 ucts fuse with an individual cell of the kind that gave rise to them, it would be 

 quite natural to regard them as being phagocytic, while, as a matter of fact, the 



