284 D. D. CUNNINGHAM. 
as a rule, to follow a somewhat different, course according as it 
takes place within or without a host-body. In media external 
to the body the spore-cells generally give direct origin to 
Ameebule, which in their turn produce a new generation of 
sporangia. Now, certainly, any true sporangial formation never 
occurs within the body, indeed, it is scarcely possible that it 
should occur seeing that the constant movements of the medium 
must mechanically tend to prevent the initial aggregation of the 
formative units. It is notso easy to determine to what extent any 
new spore formation takes place at all, or how far the entering 
spores normally assume an amoeboid condition on emergence, or 
whether the zoosporic condition replaces the amceboid one as it 
does in certain cases external to the body. That they sometimes 
do give origin to Ameebze, and that the latter, although failing 
to produce sporangia, may, in some cases, develop a new 
generation of reproductive elements, seems to be clear; but it 
remains undetermined how far this is a normal event. The 
question is, does an amceboid stage normally intervene between 
the entering spore and the zoosporic elements abounding in the 
lower portion of the intestinal tube? In other words, are the 
zoospores there the products of spores developed in Amebe 
derived. from the extraneous reproductive elements, or are they 
directly derived from the latter? is the flagellate zoospore the 
normal form assumed by the reproductive elements within the 
body as the Ameeba is external to it? This is a question which 
cannot, in the meantime, be definitely answered. There seems 
to be no doubt that zoospores, in certain circumstances, are 
developed as the normal product of the intra-intestinal Amebe ; 
but this of course does not exclude the possibility of their 
coincident development from extraneous spores also. 
It now remains to consider the relation which the presence of 
the parasite bears to cholera and other morbid conditions with 
which it appears to be specially associated. It may be asked 
why any special association should occur if the reproductive 
elements of the organism are so generally diffused and so con- 
stantly liable to be introduced into the digestive tube as they 
appear to be. The answer to this question appears to be as 
follows :—The special prevalence of the parasite in the excreta 
in cholera and other intestinal disorders seems to be determined 
by the abnormal characters of the intestinal contents. 
With regard to this point it may be sufficient to recall the 
fact that the alkaline choleraic fluids may be readily demon- 
strated to be an efficient nutritive medium—a medium much 
more favorable to the parasite than the material of normal 
excreta is. They have frequently been employed as such in the 
study of the parasite as present in normal excreta, and again 
