xIv,2 Haughwout and de Leon: Erythrocyte Ingestion 915 
In the material we were able to study we saw no individual 
in which we could detect bacteria such as one may find in the 
general run of lumen-dwelling forms. If we had encountered 
merely one or two individuals containing erythrocytes, we should 
have been inclined to place less weight on the observation, be- 
cause trichomonads will frequently take in rather large bodies. 
(Kofoid and Swezy(9) figure Trichomonas prowazeki from the 
gut of Diemyctylus torosus with an engulfed “Blastocystis enter- 
ocola” fully half the size of its own body.) But here the senior 
author counted 103 individuals containing erythrocytes and 
observed many more, while the junior author likewise saw a 
large number. There was every apparent evidence that the 
ingestion of the corpuscles was not fortuitous, but was “pur- 
poseful” to the extent that the parasites literally seemed to “go 
after” the corpuscles; and, furthermore, the variation in size 
of the corpuscles contained in the bodies of the parasites sug- 
gested, on the analogy of Entameba histolytica, that they were 
being digested and assimilated. It should be noted, further, that 
the cytoplasm of the organisms bore a distinct greenish tint 
such as is seen very frequently in Entameba histolytica and is 
thought to be due to the breaking down of hemoglobin. To be 
sure, this greenish tint is occasionally seen in Entameba coli, 
according to some authors. 
This seems to us to open a new line of attack on the general 
problem of the pathogenicity of the trichomonad flagellates found 
in the intestine of man. This group comprises three genera: 
Trichomonas (sensu stricto), with three anterior flagella; Te- 
tratrichomonas, with four anterior flagella; and Pentatrichomo- 
nas, with five anterior flagella. All are equipped with an 
axostyle and an undulating membrane bearing a marginal fla- 
gellum which is continued beyond the posterior end of the body 
as a free Jash.° 
On the basis of our present knowledge, Trichomonas and Te- 
tratrichomonas seem to be lumen-dwelling forms subsisting solely 
on bacterial life. But now Pentatrichomonas appears as a form 
adapted to the rather specialized diet of erythrocytes and, so 
far as we can see in this instance, gives no evidence of being 
* As the proof on this paper is being read we have discovered a tricho- 
monad and an associated spirochaete in the exudate removed by aspiration 
from the pleural cavity of a Chinaman in the Philippine General Hospital 
a few hours before death. We are unable at this time to offer an 
explanation as to how the flagellate gained entrance to the pleural cavity; 
but, the case having gone to autopsy, we shall report in detail on it in 
the near future. 
