338 
Parasite of East Coast Fever 
The escape of parasites from infected corpuscles was recorded on six 
occasions only. In no case did any injury of the corpuscle accompany 
the escape of the parasite. In three instances we were dealing with a 
singly infected corpuscle, in two instances with a doubly infected 
corpuscle, in one instance the corpuscle contained four parasites. In 
the cases of the two doubly infected corpuscles both parasites escaped 
from the one corpuscle and only one parasite escaped in the other 
instance. From the corpuscle containing four parasites two of the latter 
were “shot out” at opposite sides of the corpuscle. All three of us had 
an opportunity of observing the escape of parasites from corpuscles. 
On the other hand, only one of us (A. P.) has seen parasites escape 
and re-enter fresh corpuscles ; the observation was made on but two 
occasions. In the first instance (Cow 1, 20th day, 10°/o °f r.b.c. 
infected) an ovoid parasite escaped and immediately indented and 
re-entered a fresh corpuscle, 24 minutes after the blood had been drawn 
(observation at 37° C.). In the second instance (Cow 1, 21st day, 16°/ 0 
of r.b.c. infected) a rounded parasite escaped 13 minutes after the 
blood was drawn and after zigzagging about in the serum for 15 minutes 
it penetrated a fresh corpuscle; although observed, subsequently, for 
nearly an hour no further development followed. 
Conclusions and Summary. 
The mere fact that East Coast Fever is not communicable by 
blood inoculation indicates that the infection does not occur through 
the escape of parasites from infected corpuscles and their entry into 
fresh corpuscles, as in true piroplastnosis. Judging, however, from two 
observations made by one of us (see previous section) the parasites may 
at times escape and re-enter corpuscles. How are these conflicting 
statements to be brought into accord ? If it is true that the escaping 
parasites actually re-enter fresh corpuscles under natural conditions, then 
the non-communicability of the disease can only be due to the parasites 
being incapable of fui’ther multiplication in the freshly invaded corpuscles, 
and the phenomenon of their escape and re-entry is without significance 
either in relation to the disease or to the biology of the parasite. The 
question then arises : How do the corpuscles become infected ? 
Although the significance of “Koch’s bodies” in the spleen and 
other internal organs of animals infected with East Coast Fever is still 
obscure, one of us (G. H. F. N.), acting on the assumption that they 
may bear a causal relationship to the disease, inoculated a fresh 
