334 
Parasite of East Coast Fever 
observers agreed that the parasite had apparently grown slightly in size 
during the interval. The parasite was ovoid in form throughout, except for 
a couple of minutes (52—54'), when it appeared to protrude a bud-like 
process which grew in length and became narrower than the body of the 
parasite. I he parasite then resembled a tetanus bacillus with a 
terminal spore (drumstick), but the process was soon retracted. In 
Diagram 1 B one observer (H. B. F.) recorded the movements of a small, 
single pear-shaped parasite during a period of 20 minutes (44'_64'). 
In both cases the parasite “ explored the interior of the corpuscle in 
all directions. 
Similar observations were repeatedly made, but these figures will 
suffice to record the nature of the movement. Apart from “ tacking 
about ” at certain points the parasite occasionally rolled over. At times 
it moved with a fair degree of rapidity from one point to another, at 
other times it moved about slowly. The parasite was very distinctly 
seen as a rule, but occasionally it grew dim as in a fog owing, apparently) 
to the intervening haemoglobin, the parasite having wandered to the 
opposite side of the corpuscle. 
The alteration in form observed in single parasites could be 
frequently attributed to their rolling over and being viewed in a 
different position. At other times we believed that what appeared to 
be processes were nothing but temporary creases in the corpuscular 
membrane giving rise to optical delusion. At other times, however, we 
were convinced that the parasites underwent actual alterations in form 
(Diagrams 2 and 3 A); the changes of form were slow and slight and 
not in any way to be compared to the active amoeboid movements of 
Piroplasma canis at certain stages of its development, as recorded by 
Nuttall and Graham-Smith. In most cases no distinct changes of form 
could be observed after prolonged observation lasting, in some cases, for 
hours. Similar appearances were seen in the case of corpuscles which 
contained two or more parasites. (Diagram 4.) 
As in the case of P. canis and P. bovis no structure can be made out 
in the living parasite, and this appears natural in view of the extremely 
small size of the organism. 
In no case could we satisfy ourselves that intra-corpuscular parasites 
underwent multiplication. What appeared to be division was, indeed, 
repeatedly observed (Diagram 3, Series B and C). The parasite 
assumed a double pyriform shape, the swollen portions (B 31', C 217') 
remaining connected by a strand of protoplasm. Such forms were at 
times observed for several hours, but no further change of form took 
