226 
INGESTION OF ERYTHIIOCYTES BY 
TRYPANOSOMES. 
By HARALD SEIDELIN, M.D. 
(With Plate XVIII.) 
On examining fresh specimens of white rats’ blood containing 
numerous trypanosomes of a strain {T. brucei group), for which I am 
indebted to Dr J. W. Scott Macfie and with which I was experimenting 
at the Medical Research Institute at Yaba, Nigeria, I was struck by 
the energetic way in which the parasites attacked the red blood cor¬ 
puscles. They sometimes adhered to the corpuscles for a long time, 
moving them about in different ways, and sometimes appeared to 
pierce their membrane, now in one place, now in another, penetrating 
more or less deeply into their substance. A careful search of a number 
of stained films revealed in some the presence of very interesting 
appearances which seem to establish the important fact that these 
trypanosomes are capable of ingesting and digesting erythrocytes. 
The accompanying figures, which are all from one and the same specimen 
taken six days after intraperitoneal infection, show that the parasite 
encircles the erythrocyte, which gradually becomes enclosed in its 
protoplasm, probably in a sort of vacuole which develops between the 
two nuclei. The erythrocyte becomes more or less disintegrated and 
gradually reduced in size ; its characteristic staining remains for a long 
time recognizable, but the final result is a vacuole with homogeneous, 
almost unstained contents, between trophonucleus and kinetonucleus. 
It is not probable that this phenomenon is of common occurrence; 
as far as I am aware, it has never before been described. It may, 
however, be mentioned that in a paper by Carini (1910, Ann. Inst. 
Pasteur, xxiv. 143-151), describing intracorpuscular forms of various 
trypanosomes, two figures (29 and 30) might perhaps more correctly 
be interpreted as showing digestion of erythrocytes. It is likewise 
