PLASMA CELLS OF HOFBAUER 339 
to attention later, the percentage becomes 26.7; that is, 30 out 
of 112 cases of hydatiform degeneration. Of these thirty cases 
containing Hofbauer cells in sufficient numbers to attract atten- 
tion in the course of a routine examination made for other purposes, 
seventeen or 56.6 per cent, were later identified as instances of 
hydatiform degeneration. Since the sixty-one cases in the first 
series were examined especially for the purpose of study of Hof- 
bauer cells, the higher percentage of correlation observed in 
this series may be due partly to this fact. At any rate, that 
such a correlation exists seems to be quite clear, although I do 
not conclude that the two conditions necessarily or invariably 
are associated. 
It is interesting that Pazzi (’04) considered a distrophy of 
the connective tissue with the development of cellular elements 
“not very well differentiated, but like the plasma cell of Hof- 
bauer,” as the initial and pathognomonic change in hydati- 
form degeneration. Pazzi further stated that the plasma cell 
of Hofbauer may be in a state of hyperactivity or of de- 
generation, and questioned the statements that Hofbauer cells 
appear only at the end of the fourth week and that they have a 
short life. Pazzi regarded the Hofbauer cell as fundamentally a 
constituent of the villi, as the decidual cell is of the decidua. 
He, like Essick, attributed their origin to the endothelium of 
the vessels, and Pazzi suggested that the Hofbauer cell may have 
a special internal secretion intended to preserve the stroma of 
the young villus against degeneration. Pazzi further considered 
the question whether a Hofbauer cell can transform itself into an 
epithelial cell and finally into a syncytial cell, adding that the 
invasion of the stroma of the villus by epithelial growth, is only 
a special development of Hofbauer cells! 
As already stated, Muggia also found these cells very abun- 
dant in a case of partial hydatiform degeneration, and held that 
their appearance and condition was correlated with the pro- 
liferation and vacuolation of the syncytium, maintaining that, 
as the latter becomes vaculolated the lipoid interstitial cells 
of Acconci appear, the changes in the two being wholly parallel. 
