236 D. D. CUNNINGHAM. 
As previously mentioned, the occurrence of amcebal organisms 
in choleraic and other excreta was recorded by Dr. Lewis and 
myself, in the years 1870, 1871.1. The only other accurately 
recorded observation regarding them appears to be that of 
Lésch, published in 1875, in which organisms associated with a 
dysenteric condition of the large intestine, are assumed to have 
been the specific canse of the disease, and have received the 
name of Ameba coli.” 
In so far as morphological characters are concerned, the 
monads observed in excretal materials in Calcutta in some cases 
agree with the genus Cercomonas, and seemingly represent the 
so-called Cercomonas intestinalis, Dav. In others, however, 
they seem rather to correspond with the genus Trichomonas, 
taking the characters of the latter as defined by Stem. This 
authority denies the presence of any true lateral cilia, and 
maintains that the appearance of a ciliated border is deceptive, 
and really due to the rapid emission of successive protrusions 
from the soft body substance of the organism.2 Whether 
this be true of all the organisms at present united under 
the generic term Trichomonas I am unable to form any opinion 
from practical experience ; but certainly the phenomena pointed 
out by Leuckart in reference to Trichomonas bactrachorum 
are opposed to such a belief. In reference to the organisms 
with which we are at present concerned, however, I can with 
the utmost confidence assert that Stein’s description is strictly 
applicable. This being so, it is clear that, unless the lateral 
cilioid protrusions are constantly emitted, which is certainly not 
the case, the same organism must at different times present the 
characters of both genera, Cercomonas and Trichomonas. Not 
only does our parasite do so, but it presents a protean series of 
immediate forms, as well as another series connecting it with 
the form-genus Ameeba. This latter series presents characters 
practically undistinguishable from those of the swarm-spores of 
the Myxomycetes, a group of organisms with which the parasite, 
as we shall find, presents other close points of agreement. 
Before going further, it may be well to describe the characters 
of these monads, or, as they may with more propriety be 
termed, zoospores, a little more closely, even though I have 
comparatively little to add to the descriptions of them previously 
given by both Dr. Lewis and myself several years ago. In 
regard to form, it is difficult to make any definite statement in 
reference to organisms which in this respect exhibit no constancy, 
1 Op. cit. 
2 Archiv fiir pathol. Anat.,’ 1875, Bd. 65, 8. 196. 
3 Quoted in Leuckart’s ‘Die Parasiten des Menschen und die von 
ihnen herriihrenden Krankheiten,’ Zweite Auflage, 1879, 8. 311. 
