112 CARNEGIE INSTITUTION OF WASHINGTON. 



no one has sho>^Ti that they do so in fixed material. This difference, 

 however, niay be due to the degree of differentiation. Since the end- 

 form of the Hofbauer cell is a mere shadow, it may at times be impossi- 

 ble to determine from what type of cell it originated. This may also 

 account for the \'iew that these cells are degenerating blood-cells. Meyer 

 could find no evidence to support the theory that they are of endo- 

 thehal origin. Although often Ijdng near or even in extravasations in 

 the villi, they never were found engorged with erythrocytes or pig- 

 mented. The material examined showed their presence in villi whose 

 blood-vessels contained no erythroblasts, and also in non-vascular 

 villi. Degenerating erythroblasts, identical in appearance to Hof- 

 bauer cells, are occasionally seen in the vessels and even in the heart 

 itself, but there is no proof that in the villi Hofbauer cells arise from 

 erythroblasts. 



Undoubted instances of phagocytic Hofbauer cells were never 

 observed, although pseudo-phagocytosis was encountered; i.e., binu- 

 cleated cells in which one nucleus had undergone complete chroma- 

 tolysis, leaving only a nuclear membrane. Nevertheless, if they arise 

 from mesenchyme, Hofbauer cells may be potentially phagocytic, and 

 failure to find them so may be due to a lowered vitality in consequence 

 of degenerative changes. In some cases Hofbauer cells fuse and form 

 large, multinucleated, and sometimes vacuolated complexes. Although 

 closely simulating phagocytosis, these degenerate fusion products can 

 not be regarded as living giant cells. They seem to be indicative of 

 degeneration and death rather than of regeneration and life. 



While Hofbauer cells do not wander in the sense of the leucocyte, 

 they nevertheless do change their location decidedly. Therefore, 

 Meyer considers that the term wandering cell, being a non-committal 

 one, is less objectionable than either lipoid interstitial cells or giant 

 cells. Since they are most frequently found in degenerate villi and 

 not uncommonly lie in detritus, he regards these typical, vacuolated 

 elements as degeneration products. Cells morphologically identical 

 to them can be found elsewhere than in the localities mentioned, but 

 we are not thereby justified in designating these as Hofbauer cells, 

 unless we wish to extend the use of that term to degenerating and dis- 

 integrating cells of all origins. 



In order to determine the distribution of clasmatocytes in the chick 

 embryo of about 7 days' incubation, Mr. C. S. Beck made living 

 mounts, consisting of small bits of tissue from the various organs 

 placed in Locke solution to which had been added a little neutral red. 

 He found that the clasmatocytes are present in the greatest number in 

 the subcutaneous tissues, where they lie everywhere enmeshed in the 

 loose reticulum. There are none in the epidermis. Thej^ are abundant 

 in the submucosa of the alimentary tract, and are also numerous in the 

 subserous tissue. There are some among the muscle-bundles of the 



