354 
ARRIGO VISENTINI. 
regard to which Gi-assi, in collaboration with Foa, has 
described a whole complicated system of organellas in Joenia, 
'Jb’ic honympha, and other Protozoan parasites of Termites. 
My investigations, begun in the Laboratory of Comparative 
Anatomy at Rome, were continued by me during my stay in 
the Institnt fhr Schiffs- uud Tropenhygiene at Hamburg, and 
were resumed, after some interval, in the Protozoological 
Department of the Lister Institute of London by the express 
desire and advice of Prof. Minchin. To Profs. Grrassi 
and Minchin, who have directed and guided me in a field of 
study almost new to me, I desire to express my gratitude. 
Investigations on the finer structure of Leishmania in 
the Leptomonas form are almost entirely new, especially 
for the Leishmania which is the specific agent of kala- 
azar in the countries of the Mediterranean basin and which 
goes under the name of L. infantnm. None of those who 
have occupied themselves with the morphology of this Proto- 
zoon in the flagellate stage have made use of those methods 
of histological technique which alone permit a study of the 
7iiinnte stimcture of Protozoa, a,nd have limited themselves 
rather to describing the various fonns which are met with in 
the culture-tubes, some of them trying especially to recon- 
struct the developmental cycle of the pai'asite. But the data 
with regard to the developmental cycle of the parasite are 
more than ever uncertain and contradictory; as is known for 
other flagellate Protozoa, the cultural forms are for the most 
part aberrant or resting forms, and it is probable that many 
of those described in the cultures of L ei slunan ia may be 
regarded rather as degenerative fonns. On the other hand, 
concerning the structure of the parasite there have resulted 
many inexact observations. 
Of great interest are, above all, the questions regarding the 
significance of the blepharoplast and its exact relations Avith 
the flagellum. Rogers has described in the first days of the 
development of L. donovaniin acidulated citrated blood, 
a body which stains with eosin, for the most part rounded or 
oval, closely apposed to the blepharoplast, which is now 
