i20 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
Preparations of blood and bone-marrow made at autopsy showed no parasites. 
Organs appeared normal. 
Ex. 156: Adult rabbit, weight 2,407 grammes. 
Much over 500 ticks, many of them certainly infected, have fed upon this animal. 
On Dec. 10 it was inoculated with blood containing- numerous spirochaetes. Its blood 
was examined daily up to the end of December, and occasionally since. Parasites have 
never been seen. 
GUINEA PICS. 
Ex. 155 : Guinea pig, weight 453 grammes. 
Was inoculated on Nov. 15, Nov. 17, Dec. 2, Dec. 10, and Dec. 17 with small quan- 
tities of blood containing spirochaetes, taken from patients or experimental animals. 
Daily examinations were made, but parasites were never seen. On Ian. 23, 4ccm. of blood, 
showing one spirillum to field (as before i-i2th immersion and No. 4 ocular), taken from 
an infected monkey, was inoculated. Parasites in very small numbers were seen during 
the two succeeding days and not again. 
RATS. 
Ex. 162 : Adult rat, weight 266 grammes. 
Dec. 5 to 12. — Twelve of the ticks which infected Ex. 157 were repeatedly fed on 
this animal. Dec. 13. — Spirochaetes seen in blood. Parasites were continually present 
until Dec. 19, when animal died. Death was undoubtedly largely due to a large, 
traumatic, subcutaneous abscess. 
Ex. 163 : Young rat, weight 65 grammes. 
Dec. 10. — Inoculated with 3ccm. blood, containing numerous spirochaetes taken from 
an infected monkey. The blood was examined daily until Dec. 29. Parasites were seen 
in large numbers only on Dec. 12, 13, 14, 17, and 19 (not examined on Dec. 11). 
Ex. 166: Adult rat, weight 168 grammes. 
From Dec. 19 to 31, the ticks used in Ex. 162 (see above) fed repeatedly. The rat 
did not become infected. On Jan. 23 it was therefore inoculated with 3. seem, cf blood, 
containing numerous spirilla, taken from an infected monkey. The blood was examined 
daily until Feb. 1, and since then at intervals of a few days. Very scanty parasites were 
seen only on Jan. 26, 27, 30, and Feb. 1. 
Ex. 185 : Rat, young-, weight 91 grammes. 
Jan. 23. — Inoculated with 2. seem, blood, containing many spirochaetes, from an in- 
fected monkey. Blood was examined daily until Feb. 1, and at intervals since. Para- 
sites were seen on Jan. 24, 25, and 26. 
MONKEYS. 
We have been able to infect monkeys, five Cercopithecus ( ISchmidti), one 
CercopitJiecus campbelli, and one Cercopithecus (Sp. ?), with spirochaetes by the bites of 
ticks. Each animal was examined with negative result before the commence- 
ment of the experiment. Thirty other monkeys of the same speciesi caught in the same 
districts, and kept under the same conditions have been used for other experiments. 
Their blood has been constantly examined, and none have ever been found to be infected 
with spirochaetes. 
Fx. 157: Young Cercopithecus, weight 1,586 grammes. (Chart No. 8.) 
Nov. 19, 20, and 21. — Ticks (231 in all), caught in native houses at Nyangwe were 
allowed to thoroughly feed on this animal. On Nov. 24 spirochaetes were detected in its 
blood. The parasites later increased greatly in number. There was a high temperature. 
The monkey became very thin and weak. Anaemia was very pronounced, and death 
occurred on Dec. 4, after two days of utter prostration, during which the monkey 
scarcely moved, but remained dozing, crouched en his haunches. The autopsy was 
done immediately after death. Blood was very pale, and all organs anaemic. Long bone- 
