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Hciematozoa 
an infected horse on 3. V. 1897. Thereafter, though their blood was 
examined frequently, and though their temperatures showed occasional 
irregular rises, no trypanosomes were found in their blood. It may be 
presumed either that the infecting blood was at fault, or that they were 
resistant individuals. The sequel is somewhat in favour of the latter 
view. It may be noted here, that on the 43rd day after this first 
inoculation, rats were injected with the blood of each guinea-pig with 
negative result. 
Guinea-pig “ A ” was reinoculated by the late Dr Kanthack on 
10. II. 98 with blood of a guinea-pig containing active trypanosomes. 
Its blood was examined at intervals, and from 6. ill. to 8. vi. 98 the 
presence of the trypanosome was noted. From that day onward 
trypanosomes were absent, so that on 24. Xl. 98, this guinea-pig was 
again inoculated, the blood of an infected rat being used. The period 
covered was already more than nine months since the inoculation which 
had shown itself to be successful. Seventeen days after this third 
inoculation the blood was free from parasites, but by 24. II. 99 the 
trypanosome had become common, and the animal seemed to be ill. 
Eventually it died on 3. ill. 99 or 99 days after the last inoculation. 
At the autopsy, the lymphatic glands were found to be exceptionally 
enlarged for a guinea-pig, the spleen was also much more enlarged than 
usual; in fact the appearances recalled those which obtain in the rat. 
The further notes on guinea-pig “ B ” have unfortunately been lost. 
Observations on another pair of guinea-pigs (“ C ” and “D”) may 
be cited; these were first inoculated by Dr Kanthack on 22. II. 98 from 
an infected guinea-pig. 
Guinea-pig “C” showed that it had been successfully infected, as 
trypanosomes were present in its blood 62 days later ; eventually it died 
of the infection on the 102nd day. 
Guinea-pig “ D ” is of greater interest. Trypanosomata were dis¬ 
covered in its blood 44 days alter inoculation and again on 15. IV. and 
25. iv. 98. Subsequent examination twice or thrice a month failed to 
reveal parasites. On 24. xi. 98 it was again inoculated, this time from 
a rat. Unfortunately on 20. II. 99 it was given another inoculation. 
On 8. in. 99 and again on 21. ill. its blood was crowded with trypano¬ 
somes. Death occurred three days later. Counting from the original 
infection, the animal survived no less than 13 months, whilst the sur¬ 
vival after the first reinoculation was 120 days; it may be noted that 
this infection was done from the same rat that served in the case of “A.” 
It would seem then that although individual guinea-pigs may show 
