ARRIGO VlSENTINl. 
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so that the oue may be already finished when the other is 
beginning, and if they take place synchrononsly, they may be 
found in different stages. Moi’eover, I have never observed 
a fusion of the kinetonucleus with the principal nucleus, as 
Row has described in the cultures of Leish mania tropica, 
not even in the first days of the development, when the 
flagellated forms are arising from those of the spleen. 
With regard to the first origin of the flagellum my 
observations are very scanty, since I have only twice 
obtained cultures of spleen-material, but I am able to confirm 
the descriptions given by other authors, and to state pre- 
cisely the manner in which the flagellum exists. 
Bes’innino- with the small forms of Leishmania from the 
O O 
internal organs of kala-azar patients, and especially those in 
which the rhizoplast can already be demonstrated (figs. 7, a, 
B, of my memoir [26] ), the next stage has a more rounded 
form, or is already pear-shaped (see fig. 38) with a more 
distinct rhizoplast. The flagellum begins to protrude from 
the body of the parasite and becomes continually longer, 
while the organism becomes pyriform and elongated, and the 
kinetonucleus, which at first was found by the side of the 
nucleus, passes anteriorly to it. In this way there are flagel- 
lates of more or less elongated form with one end pointed 
and the other, the anterior end, rounded, and also long and 
very slender forms such as that represented in fig. 21. 
The protoplasm of Leishmania iii cultures appears, with 
the best fixatives, very finely gi-anular, and contains frequently 
here and there granules of various sizes, identical with the 
volntin-grains of trypanosomes. After prolonged colora- 
tion with Heidenhain’s luematoxylin of smears fixed in 
Schaudinn’s fluid, the protoplasm often assumes a variegated 
appearance, with patches intensely coloured and separated 
by clear spaces. 
I have never observed in the protoplasm the existence of a 
filament uniting the kinetonucleus to the trophonucleus, as 
described by Prowazek and some of his pupils, amongst 
them also recently Chagas in Trypanosoma cruzi. After 
