TRYPANOSOMES, TRYPANOSOMIASIS, AND SLEEPING SICKNESS 93 
ADDENDUM (see p. 13) 
Note 011 the effect produced on rats by the trypanosomata of Gambia fever and 
sleeping sickness, by H. G. Plimmer, F.L.S., communicated by Dr. C. J. Martin, 
F.R.S. Received December 1, 1904. Read January 19, 1905. — Proceedings of the 
Royal Society, T. LXXIV, No. 504, February 24, 1905, pp. 388-390. 
Synopsis of the Paper : — 
Gambian Fever. Fourteen rats 
Parasites appeared about four weeks after inoculation. Duration of disease, two months twelve 
days. Parasites present in large numbers towards end. Paralysis. Nervous symptoms, none ; 
before death, animal heavy and apathetic. 
Sleeping Sickness. Three rats 
Parasites never found in the blood. Duration, six to nine months. Paralysis — 
Both hind legs May 12, death May 23 
„ „ Aug. 2, „ Aug. 30 
„ „ Aug. 28, „ Sept. 8. 
Post-Mortem 
Spleens not enlarged. No microscopic lesions. The blood was citrated and centrifugalized, 
and the organs were mashed and washed with normal salt solution and centrifugalized, but in 
no case were an}' trypanosomata found. Portions of the extracts of liver and spleen and spinal 
cord were injected into other rats, but up to the present these show no sign of illness. In an 
addendum, December 14, 1904. Two of the three rats inoculated developed paraplegia. The 
blood examination of these animals fails to discover any trypanosomata. Apart from the 
paralysis the animals show no sign of ill-health. In the mashed spinal cord of each of the 
rats the characteristic trypanosomata were found in small numbers, but none were found in the 
brains which were examined in the same way. 
Mr. Plimmer concludes 
1. ' These experiments go to show that the two diseases — Gambia Fever and Sleeping Sick- 
ness — from which the organisms were obtained, are distinct ; the duration of the disease, the 
symptoms and the post-mortem appearances being quite different. It is evident that these two 
organisms are quite separate and distinct, as their different effects on similar animals indicate. 
The fact of the clinical observation that Gambia fever not infrequently appears to terminate with 
all the symptoms of sleeping sickness may quite possibly be explained by a double infection. 
For, in both rats and monkeys, the one trypanosoma does not interfere with the other, but the 
more active organisms — that of Gambia fever in the case of rats and monkeys — kills in about 
the same time, whether inoculated before, with or after that of sleeping sickness.' 
2. ' There can be no question, from the above experiments, of the susceptibility of the rat to 
the trypanosoma of sleeping sickness.' 
3. ' These experiments show that the inoculation of the trypanosoma of sleeping sickness 
into rats gives rise to no obvious symptoms for many months, nor are trypanosomata discover- 
able in the blood by microscopic examination. But after a period of from six to nine months 
paraplegia occurs, leading to the death of the animal ; and post-mortem the organisms 
are found only in the spinal cord. The organisms are thus in rats, as sometimes in man, 
entirely confined to the nervous system ; where, as in monkeys, they are, in my experience, 
always generalized at some period of the disease.' 
In this laboratory more than seventeen rats have been used in the research. The 
following tables show the behaviour of the parasite in a few of the rats infected with 
the variotis strains. The third column gives the record of the parasite as proved by 
microscopical examination. 
