67 
SOME OBSERVATIONS AND EXPERIMENTS ON INSECT 
FLAGELLATES, WITH SPECIAL REFERENCE TO 
ARTIFICIAL INFECTION OF VERTEBRATES. 
(A REPORT TO THE DEPARTMENT OF SCIENTIFIC AND 
INDUSTRIAL RESEARCH 1 .) 
By CECIL A. HOARE, B.Sc., 
Late Assistant Lecturer at the Military Academy of Medicine , Petrograd. 
(From the Wellcome Bureau of Scientific Research.) 
CONTENTS. 
• PAGE 
I. Observations oil Crithidia melophagia and its relation to the sheep- 
trypanosome ......... 67 
II. Experiments on artificial infection of different vertebrates with 
insect flagellates ........ 70 
A. Experiments with mice ...... 75 
B. Experiments with fish . . . . . . 76 
C. Experiments with amphibians .... 80 
III. Observations on the vitality of some insect flagellates . . 81 
Conclusions .......... 82 
I. OBSERVATIONS ON CRITHIDIA MELOPHAGIA AND ITS RELATION 
TO THE SHEEP-TRYPANOSOME. 
Woodcock (1910) discovered a trypanosome naturally occurring in the blood 
of British sheep. This finding was confirmed by Behn (1911, 1912) in Germany. 
In both cases the authors did not give any description of the parasite, which 
was seen by them only in single cases, and they failed to cultivate the trypano¬ 
somes. 
According to Woodcock (1910) the trypanosome represents a develop¬ 
mental stage of Crithidia melophagia Flu, 1908, parasitising the gut of the 
sheep-ked, Melophagus ovinus. As the “ked” is a typical blood-sucking 
insect, and the degree to which it may be infected with these flagellates 
1 The observations here described were made at the Wellcome Bureau of Scientific Research 
with the aid of a grant from the Department of Scientific and Industrial Research. I take this 
opportunity of offering my warmest thanks to the Director of the Bureau, Dr Andrew Balfour, 
C.B., C.M.G., for his hospitality and kind assistance, and to Dr C. M. Wenyon, C.M.G., C.B.E., 
M.B., B.Sc., who has given me unfailing help and valuable advice in the course of my work. I 
am also indebted to Dr Wenyon for performing the inoculations for me, as I had not at that time 
obtained a Licence for such experiments. 
2 
