C. A. Hoare 
71 
Recently, numerous works have appeared dealing with artificial infection 
of vertebrates with the flagellates of different insects both associated and 
unassociated with vertebrates. The majority of these are by Laveran and his 
collaborators, and Fantham and Porter. These observers claim to have proved 
that insect flagellates, when introduced into vertebrates, evoke in the latter 
symptoms of disease comparable to Leishmaniasis, and assume in them forms 
similar to the leishmania parasites. 
I have repeated some of the experiments mentioned, and conducted others 
with new flagellates, but have failed entirely in producing any form of disease, 
or in finding any forms of the flagellates introduced into the animals experi¬ 
mented upon. These experiments have, however, led to certain observations 
on the vitality of the parasites thus introduced. 
As the question of such artificial infection is of considerable interest, and 
important theoretical and practical conclusions have been deduced from them 
by the authors mentioned above, I propose to give a short description of my 
experiments, together with a brief review of the results arrived at by these 
authors. 
The following are the species of flagellates with which such experiments 
had been made: 
1. Herpetomonas pattoni. 
2. H. ctenopsyllae. 
3. H. ctenocephali. 
4. H. phlebotomi. 
5. H. muscae-domesticae. 
6. **H. calliphorae 1 . 
7. *H. jaculum. 
8. H. stratiomyiae. 
9. H. pediculi. 
10. Crithidia fasciculata . 
11. *C. melophagia. 
12. C. tabani (?) 
13. C. gerridis. 
For the sake of convenience I have reproduced, in Table I, the methods 
and results of experiments on artificial infection of vertebrates by various 
authors. As far as I could ascertain, this Table contains all the chief experiments 
on this subject (with the exception of some similar experiments on birds). 
It can be seen from this Table that some of the workers have succeeded in 
introducing flagellates from insects into various vertebrates, and have evoked 
in them infections similar to Leishmaniasis, both as regards the morphology 
of their parasites and, in some cases, the lesions as well. Successful results were 
obtained with flagellates both from insects which are naturally associated with 
vertebrates and those which have no such association. 
In the animals thus infected, the flagellates are said to make their 
appearance in the blood and organs in the form of leishmania and flagellate 
bodies. Infection of mice frequently terminates in death, and examination of 
organs post mortem shows that some of them (spleen and liver) are hyper¬ 
trophied. 
1 Asterisks denote species which were used in my experiments as well; the species marked with 
two asterisks had not been used by previous workers. 
