378 
DR. AERIGO VISENTINI. 
those alteratious which are produced by the simple fact of 
operative lesion. With regard to this I can confirm the 
observation of Delanoe for trypanosomes. When the punc- 
ture of the peritoneum is repeated several times, alteration 
and death of the Leishmanias take place by the probable 
extrusion of trypanolytic substances from the leucocytes into 
the plasma, while if the peritoneum be not punctured the 
flagellates that have remained free are preserved living and 
with normal structure, and in this condition are engulfed by 
the leucocytes. 
Of the liquid extracted from the pei'itoueal cavity I have 
made preparations in the fresh condition and smears on slides 
which I have fixed while still wet in vapour of osmic acid for 
five seconds, and afterwards, when dry, in absolute alcohol 
for a quarter of an hour — a method of technique which also 
gives very good results for staining the flagellates in the 
cultures. The smears should be very thin, and it is often 
useful to follow the staining by very short differentiation in 
the solution of tannin according to Unna. 
I have made examinations of the peritoneal liquid every 
five minutes after the injection up to two hours and then 
every half hour up to four hours, repeating the experiment 
in a fairly numerous series of animals. In the fresh state 
it is seen in the first few minutes after the injection of the 
culture that the number of the Leishmanias, truly enormous 
in 2-4 c.c. of a rich culture, is already to some extent 
diminished, and not by the fact of the greater dilution alone; 
very many flagellates are still free and very many are mobile, 
perhaps even more than in the cultural liquid, but it is not 
difficult to come upon others adhering or united to leucocytes, 
either by the posterior end or by the flagellum, preserving, 
however, in all cases a certain mobility. When they are 
completely engulfed in the leucocytes they are seen in its 
protoplasm as rounded bodies, but at this point it is easier 
to recognise them and to follow their modifications in the 
stained preparations. In the fresh state I have found in the 
guinea-pig some Leishmanias free and mobile up to an hour 
