C. A. Hoare 
83 
are protozoa (cf. Lignieres, 1919; Di Domizio, 1919). Whatever the case may 
be, there are no grounds for connecting the “anaplasma " with the flagellates. 
In the experiments of these authors and Laveran and his colleagues 
reference is frequently made to leishmania forms with only a single nucleus. 
It must be very doubtful if these can be regarded as such. In the examination 
of smears of organs, in experiments of this kind, only undoubted leishmania 
forms should be considered. According to these authors, leishmania forms are 
also produced by infecting mice with C. melophagia (Laveran and Franchini, 
1914 b, 1919 a). As Noller's (1919, 1919 a , 1920) observations have proved this 
flagellate to be a trypanosome ( T . melophagium), its inoculation into mice 
would be likely to produce in the latter trypanosomes, and not leishmanias. 
The experiments of Fantham and Porter (1915, 1915 a) are of especial 
interest in this respect. These authors have made experiments on artificial 
infection working chiefly with flagellates of insects not associated normally 
with any vertebrate animal. They claim to have proved that insect flagellates 
may be successfully inoculated into and fed to different warm- and cold¬ 
blooded animals. The flagellates become pathogenic to these animals and 
produce in them symptoms resembling Kala-azar and other leishmaniases. 
Fantham (1915, 1915a) concludes from these experiments that ‘'the 
occurrence of natural herpetomonads in invertebrates must not only be 
acknowledged, but it must be allowed that they may become pathogenic, 
when introduced into vertebrates,'' thus apparently extending the results of 
the experiments discussed to all insect herpetomonads. 
I have repeated some of the experiments recorded by Fantham and Porter 
with the negative results already described. In the case of infection of fish, 
my experiments were much more numerous and varied than those recorded 
by the authors named. In inoculating frogs, the site of injection (lymph- 
sinuses) would seem to afford the easiest point of access for the flagellates into 
the blood stream of the host. Notwithstanding these facts, I have utterly 
failed in producing even the slightest sign of infection in these animals, and 
have never found any forms of the flagellates introduced into them which 
would suggest infection. 
The conclusions of Fantham (1915, 1915 a) already quoted, and the more 
general conclusion that leishmaniases are ‘‘arthropod-borne herpetomo- 
niases” are very interesting from the theoretical point of view, and it is quite 
possible that later discoveries will prove this to be a fact, and not merely a 
hypothesis. 
The facts available at present, however, do not in my opinion permit one 
to assert that the natural herpetomonads in insects, especially in those not 
associated with vertebrates, may become pathogenic, when introduced into 
the latter, as the author suggests. 
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