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Haemoflagellates, etc. 
those species entirely limited to insects, this stage takes place by the 
parasites encysting, either in the rectums or ovaries of their hosts. We 
believe therefore that these human parasites, in order to be reintroduced 
into man, must be inoculated in their non-flagellate stages, and it is most 
probable that Novy was dealing with some of these unchanged forms in 
his cultures. This clearly explains the reason why it is necessary to 
inoculate such large numbers of flagellates iu order to produce the disease, 
while a very small quantity of splenic blood containing the pre-flagellate 
stages of H. infantum readily produces the disease in dogs and 
monkeys. 
As a result of his observations on the canine form of the disease, 
Nicolle claims that this animal is probably the source of the parasites 
which are inoculated into children through the intermediary of some 
blood-sucking insect. It is however by no means proved that Nicolle is 
dealing with a single species, the canine parasite may possibly be quite 
distinct from the infantile form; this can only be settled by finding out 
the invertebrate hosts of the parasites. With the infection in an animal 
like the dog, there ought to be no difficulty in carrying out feeding 
experiments with likely blood-sucking insects, in order to find out in 
which particular one the flagellate stage occurs. Similar experiments 
should be carried out with the human disease, and then once having 
found out the right insect, transmission experiments could be conducted 
on dogs and monkeys. So far as we are aware such experiments, as we 
have mentioned, have not yet been carried out. 
Recently we (1908) inoculated dogs with the fresh virus of Indian 
herpetomoniasis with negative results, and we pointed out that so 
far H. donovani has not been found in Indian dogs; these observations 
confirm our view that this parasite is distinct from the Algerian form. 
We have shown that many herpetomonads are identical in their non- 
flagellate stages, and that if this stage alone is studied it is impossible to 
distinguish between distinct species ; it is only by studying the complete 
life cycles of these parasites that this can be accomplished. 
The parasite of Oriental Sore in its non-flagellate stage is also 
identical with the similar stages of the above parasites. Nicolle (1908) 
has succeeded in cultivating the Algerian form of Oriental Sore on blood 
agar and shows that it does not differ to any great extent in its cultural 
forms from those of H. infantum. 
Row (1909) has recently cultivated the parasite of Delhi boil, and 
finds that though its method of development is very similar to that of 
H. donovani, it differs in some structural details. We have not seen 
