xiv,2 Haughwout and de Leon: Erythrocyte Ingestion 209 
curring in cases of protozoal infection may, in some instances, 
be due to secondary invasion of the tissue by bacteria other 
than the dysentery bacilli. 
It was quickly seen by the examiner that the flagellates in 
many instances contained erythrocytes. The finding was im- 
_ mediately communicated to the senior author and the stool spec- 
imen sent to the laboratory of parasitology. 
The observation was quickly confirmed by the senior author 
who, in the course of the examination of several preparations, 
noted 103 flagellates that had ingested one or more erythrocytes, 
some of which presented evidence of having undergone partial 
digestion—an. appearance frequently seen in Entameba histoly- 
tica containing ingested erythrocytes. More than this, the ac- 
tual process of ingestion was observed in one individual found 
in the act of taking in a corpuscle and whose progress was 
followed under the microscope for nearly an hour. , During that 
time the parasite ingested no less than three corpuscles. The 
individual that went through this performance was actively 
swimming about in the fecal débris and when first seen had 
applied its anterior extremity to an erythrocyte that was being 
drawn in through the cytostome, as shown in Plate I, fig.3. The 
operation of ingestion consumed about fifteen seconds, during 
which time the organism maintained its active movements. The 
act was one of literal deglutition. The corpuscle entered the 
cytoplasm as if drawn in by suction, though it was probably ac- 
complished by the action of myonemes or similar structures 
entering into the formation of the cytopharynx. Its progress 
may be traced by inspection of Plate I, figs. 3 to 8, which show 
the deformation of the corpuscle as it passed through the narrow 
orifice of the cytostome. In time, the corpuscle came to lie free 
in the cytoplasm toward the posterior end of the animal, where 
it produced a slight bulge in the body. The formation of a 
digestive vacuole around the erythrocyte was not observed; nor 
could any vacuoles of that nature be discovered in any of the 
other individuals seen that had taken in corpuscles. The ery- 
throcytes simply seemed to lie free in the cytoplasm where they 
were carried about in the cellular cyclosis. No individual was 
seen that contained bacteria, so far as could be made out, which 
leads us to the belief that this particular species is not a bacteria 
eater, but possibly derives its nourishment from erythrocytes and 
other tissue elements. This, of course, presupposes an adapta- 
tion to parasitism of a more complete type than we have evi- 
dence of .in the other intestinal flagellates infesting man. 
