340 Col. Sir D. Bruce and others. Infectiwity of [Nov. 23, 
Table I—Transmission of Z’rypanosoma gambiense from Sleeping Sickness 
Patients to Healthy Monkeys by Interrupted Feeding. 
No. of Glee | Lf pales No ee No. ee nate 
re a Oo ’ of flies times flies sult. 
oe of patient.| treated. | , otment, | Cf doses- eis fed. es 
2014: A | Yes | days 2 75 6 — 
2137 | B " bee Eas 2 65 7 ~ 
2144 C Al Albee Ni Bede 2 75 6 = 
2146 B y a roke 2 65 6 a 
2013 A i oilers 4 15 6 = 
2027 B _ 30 ,, 4 75 6 — 
2029 B - 30m 4 75 6 = 
2150 | C 55 30 —,, 4, 70 7 _ 
2152 | C a 30m. 4 50 a — 
2158 | B ie 30 _—,, | 4 60 6 — 
2139 B F 1 year P 70 6 _ 
2154 | B i oe. P 50 6 — 
2012 | B No Nil Nil 75 6 — 
2281 B ; 3 - 100 6 _ 
2284 B Ff - es 50 6 — 
Remarks.—These experiments are all negative—a not unexpected result now that it is known: 
that the mechanical transmission of Sleeping Sickness may be a somewhat rare event in Nature. 
The question as to whether the medicinal treatment of Sleeping Sickness patients has any 
preventive influence on this method of transmission remains unanswered. It may, however, be: 
noted that in the two untreated cases, viz., Experiment 2281, Class B, and Experiment 2284,. 
Class B, the disease was not transmitted mechanically, but, as will be seen later (Table ITI, 
Experiments 2280 and 2298), was conveyed after a period of development of the parasite within 
the fly. 
2. By Transnussion of the Disease from Sleeping Sickness Patient to Normal 
Monkey after the Parasite had Completed its Development in the Fly. 
The procedure adopted in the second method for transmitting the disease 
from a Sleeping Sickness patient to a monkey was as follows:—A cage of 
laboratory-bred flies was fed daily for five or six days upon a patient. 
suffering from Sleeping Sickness. They were then starved for 48 hours, and 
subsequently fed daily for 50 days upon a normal monkey. 
In most of these experiments the flies were dissected and examined for 
flagellates after the period of feeding upon the normal monkey. The 
monkey’s blood was subsequently examined twice weekly for one month 
after the last date on which the flies were fed upon it. 
Trypanosomes had been found at one time in the glands of all these: 
patients, but no trypanosomes were found in their blood during the time the 
flies were being fed upon them. 
In the following tables all the details bearing on each class of patient are: 
given :— 
