368 
AERIGO YISENTiNI. 
uniformity in the morphology of the parasite, with prevalence 
of the typical spindle form with the anterior extremity 
rounded, while the stumpy and rounded forms ai*e rarer, 
tliose that occur being for the most part in process of division. 
In the interior of the body the trophonucleus and the kineto- 
nucleus can be distinguished clearly, especially in forms 
which do not contain many granules. 
It is a noteworthy fact that the two nuclei of the Leish- 
mania present an identical appearance, as a dark point 
surrounded by a clear halo. When the motility of the 
Protozoa is diminished and the examination of the structural 
details is rendered possible, it is often possible to make out 
that the flagellum is continued as a rhizoplast into the body 
of the organism as far as the kinetonucleus, ending at the 
boundary of the clear halo of the latter. In the space 
between the trophonucleus and the kinetonucleus it is not 
infrequently possible to observe a body slightly darker than 
the protoplasm with contours not well defined, without a 
halo and without perceptible structure, exactly similar to the 
body which is made evident by the iron-haematoxylin stain, 
especially after osmic fixations. My attention, as is natural, 
has been drawn particularly to the search for something' 
which would correspond to the axostyle (“mestolo,” Axen- 
stab), that is to say, the so-called axial rod in the protoplasm 
between the nucleus and the posterior extremity, but I have 
never succeeded in observing it. Perhaps the rhizoplast is 
homologous with it? 
Observation in the fresh state and with very powerful 
magnification is of course very tiring, and it is above all very 
difficult to pick out details of structure in organisms so 
minute, but it is to be hoped that further researches will lead 
to new and definitive knowledge with i-egard to the finer 
structure of these flagellate Protozoa. 
The Lister Institute, 
London ; 
May 20th, 1912. 
