MICHIGAN ACADEMY OF SCIENCE. 
27 
similar results may be obtained with pure cultures of trypanosomes. 
This expectation has already been fully confirmed as regards one of 
these organisms, namely, Tr. lewisi, the parasite of the common rat. 
Several years ago it was shown that dialyzed, dead cultures of this 
organism when injected into the rat, protected this against the living 
virulent organisms. The production of an attenuated living strain which 
could be utilized as a vaccine was not realized until recently. With the 
help of Mr. W. A. Perkins we have shown that Tr. lewisi after passing- 
through about 200 generations or transplants, in the culture tube, be- 
comes attenuated so that it is no longer capable of infecting a clean 
healthy rat. Moreover, rats which have had such inoculations are per- 
fectly protected or vaccinated against infection with the virulent 
organisms. This, it may be said in passing, is the first example of suc- 
cessful immunization of a susceptible animal by means of living protozoal 
cultures. The success obtained in this instance warrants the belief that 
similar results may be secured with the other, the more strictly patho- 
genic trypanosomes. 
SLEEPING SICKNESS. 
The interest in trypanosomes because of their causal relation to such 
animal diseases as surra, nagana, dourine, and caderas was more than 
doubled by the discovery that a similar parasite was responsible for the 
fatal human disease known as Sleeping Sickness. Though known for a 
long time on the west coast of Africa, this disease attracted but little 
attention prior to the close of the last century. The commercial develop 
ment of equatorial Africa undoubtedly led to its wide dissemination. 
The apparently sudden appearance of a fatal disease which claimed its 
victims by the thousands led the governments of Belgium, England, 
France, Germany and Portugal to appoint special commissions charged 
with its study. The parasite first discovered by Forde and Dutton, in 
the blood of a river captain, on the Gambia (1901) was shortly after- 
wards found in the cerebro spinal, fluid and in the blood of afflicted 
natives, in Uganda, by the British Sleeping Sickness Commission. Since 
that time, the Tr. gambiense and the disease itself has been the subject 
of innumerable studies carried on not only in tropical Africa but also 
in European and American laboratories. The Bulletin of the Sleeping- 
Sickness Bureau which the British Government, through the Royal So- 
ciety, publishes monthly, is now in its third year of existence. An 
important function of this Bulletin is to supply careful summaries of 
all recently published papers dealing with trypanosomiasis of man and 
animals, and more especially Sleeping Sickness. The prompt and wide 
publicity thus given to the numerous researches dealing with this and 
related diseases is of the greatest possible benefit. Facts regarding the 
distribution of the 'disease, its mode of transmission, diagnosis, preven- 
tion and treatment are of vital importance if the disease is to be effec- 
tively controlled. 
The mode of transmission of sleeping sickness is one of very general 
interest and for that reason can be briefly referred to. It has been 
shown conclusively that it is spread by a biting insect, the tsetse-fly 
( Olossina palpal is). The glossinas are sanguivorous flies and live en- 
tirely, it seems, upon the blood of animals. They are known to feed upon 
crocodiles, birds, wild animals and man. If the disease was exclusively 
