THE TEANSMISSION OE LEISHMANIOSIS BY CULTURES. 377 
receptive. Exceptional at least are the observations which 
Franchini describes. He found parasites in the peripheral 
blood and free in the plasma, and similarly all the forms of 
Leishmania found in the liver, spleen and bone-marrow 
were extra-cellular. It is, however, usual in Leishmanial 
infections, by general agreement of all observers, for the 
parasites to be always or nearly always contained in the 
protoplasm of the large mononuclears, and it has not yer. 
been shown that they can occur free outside this their 
natural situation. Unfortunately the drawings which accom- 
pany the work of Franchini are so obscure and so little 
demonstrative that they do not permit one to judge whether 
one is dealing with Leishmania, the more so since the 
methods employed by the author are certainly not those the 
best adapted to obtain elective staining, but are even 
scarcely sufficient for diagnostic purposes, especially when 
the parasites, as in this case, are rather scarce. 
In order to study rather more closely the mechanism of the 
natural immunity possessed by guinea-pigs and white rats, 
and at the same time to avoid any objection to the facts 
observed by me, I have carried out a double series of 
investigations, morphological and cultural, witli the object of 
following step by stej) the fate of the flagellated forms in the 
organism of the experimental animals. 
Having injected into the peritoneum 2 c.c. and sometimes 
4 c.c. of a culture very rich in flagellated forms, I drew off 
every five minutes some peritoneal fluid with a sterile capil- 
lai’y glass tube and examined it fresh with the microscope, 
making at the same time some pi-eparations for staining. 
'Phe fact is quickly observed that the parasites undergo 
absorption rapidly by the leucocytes in the peritoneal cavity. 
Prior, however, to describing the phenomenon in greater 
detail some points of technique may advantageously be dealt 
with. I have performed the experiment on a sufficiently 
large number of animals, guinea-pigs and rats, in such a way 
as to be able to perform, in each animal, only one or two 
punctures of the peritoneum, with the object of avoiding 
