THE TBANSillSSION OF LEISHMANIOSIS BY CULTURES. 379 
or an lioiir and a half after the injection of 2 c.c. of culture 
into animals of 250 to 300 grammes in weight. In the rat 1 
did not succeed in seeing free forms after an hour and a 
quarter. 
In the stained preparations these various phenomena are 
very evident, and it is possible to follow step by step the 
various phases of alteration to which the Leishmanias are 
subjected. 
One fact which deserves special emphasis is that the 
parasites are found always in the large mononuclears and in 
them alone, that is to say in just those elements which 
contain them in kala-azar and oriental sore. In the rare 
cases in which a true polynuclear is found apparently con- 
taining a Leishmania, the possibility cannot be excluded 
that it is simply superposed rather than engulfed. In the 
protoplasm of the monouuclears they become more rounded 
in form, preserving sometimes all their constituent parts and 
traces of the flagellum. Thus it is possible in some parts of 
the preparations to have the impression that it is a case of 
simple modification of the form of the Leishmanias and that 
they have found in the mononuclears a habitat adapted to 
them ; but for the most part they present obvious alterations. 
I'he protoplasm becomes clear or turbid, the contours of the 
parasite disappear, the flagellum becomes thickened and 
breaks up; sometimes the trophonucleus or the kinetonuclens 
is wanting, or these bodies lose their sharp contours and their 
special characteristics and are reduced to shapeless masses of 
chromatin. 
After fifteen to twenty minutes very many mononuclears 
are observed containing Leishmanias profoundly altered, 
represented after twenty' to thirtv minutes by remains of 
nuclei near which a portion of the flagellum is to be noted. 
The profound modifications of the phag'ocyted parasites con- 
tinue, and after two to three hoiii-s there are found only 
chromatinic granules with masses of protoplasm stained 
intensely in reddish violet, representing the last vestiges of 
the destroyed Leishmanias. 
