G. H. F. Nuttall and G. S. Graham-Smith 135 
(2) Occasionally by the protrusion of four processes four mature 
pyriform parasites are formed from a single amoeboid form. 
(3) Sometimes a young rounded intracorpuscular parasite divides 
by simple division and gives rise to two amoeboid parasites, wbicb grow 
and divide by the protrusion of symmetrical processes each into two 
pyriform parasites, thus giving rise to four mature parasites within the 
corpuscle. Sometimes the two amoeboid parasites undergo the processes 
of division simultaneously, but not infrequently one is considerably in 
advance of the other. 
(4) It is possible that occasionally a red blood corpuscle is invaded 
either simultaneously or at different times by two pyriform parasites, 
each of which undergoes the changes described above. 
(5) Several pyriform bodies within a single corpuscle are produced 
by the division in the manner described of one or more amoeboid 
parasites. 
All parasites which have not reached the mature stage, when the 
containing corpuscle ruptures, rapidly degenerate and die in the plasma. 
The same is true of mature pyriform parasites, which do not, after 
becoming free, soon enter other corpuscles.” 
Aided by the knowledge thus gained we were able, by the examina¬ 
tion of stained films, to figure the nuclear (chromatin) changes which 
accompany each phase of division (1907, Plate II). A schematic 
representation of the mode of multiplication was given on p. 258, and is 
reproduced in this paper (p. 136). We now figure some of the more 
important stages by means of photomicrographs (see Plate XI). 
Christophers (1907, p. 17), who at the time of writing had apparently 
not seen the paper just quoted, and who seems to have formed his 
conclusions on the study of stained specimens only, thinks that besides 
the method of division w T e have described the formation of the pear- 
shaped forms by fission occurs in two other distinct ways. 
“(1) In the case of certain large parasites, characteristic of early 
invasion and infection in young dogs, the division takes place in the 
manner described by Nocard and Motas. After the chromatin has 
divided a dark line forms across the parasite in the centre of which a 
cleft is later seen. This stage gives rise to two closely approximated 
bodies. (2) A method of division, almost if not quite as common, 
takes place when a parasite is stretched across a cell. The long oval 
becomes constricted in the centre, and the two ends passing away from 
one another become two pear-shaped bodies.” 
Although we have made very prolonged and careful studies at all 
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