282 D. D. CUNNINGHAM. 
these were of large size corresponding with that of the spores. 
They swam about actively in the fluid, and in many instances 
exhibited very free amceboid changes of form while doing so. 
In all their characters they were quite indistinguishable from 
similar bodies as encountered in fresh human excreta, and like 
them were frequently observed to multiply by division. Due to 
this and to the constant emergence of new individuals, the pre- 
paration in the course of a few hours was swarming with active 
zoospores. At this time a certain number of small active ame- 
boid bodies was also present, which seemed in most cases to 
emerge directly from some of the larger spores. The prepara- 
tion was reserved and again examined on the following day. 
The margins of the fluid still swarmed with active zoospores, 
some of them of very large size, but otherwise agreeing with 
their compeers in every respect. In many of them a contrac- 
tile vesicle was clearly visible. Their movements varied greatly 
from time to time, free swimming being alternated with caudal 
adhesion, or with a crawling motion accomplished by means of 
ameeboid protrusions of the body-substance. 
The cultivation after this appeared to remain unchanged, no 
further development occurring, and the surface continuing 
covered with a thick layer of bacillar spores and of spore-cells 
derived from the Ameebe. It remained throughout entirely free 
of any fungal mycelium. 
In the majority of similar cultivations the results closely 
resembled those just described, but in one case, at all events, a 
development of well-formed normal sporangia took place, and in 
others various deviations in the form of arrested development 
occurred. The series, taken as a whole, appeared unequivocally 
to prove the identity of the organisms occurring in human and 
vaccine excreta, and also that the zoospores are merely a form 
which the reproductive bodies resulting from processes of divi- 
sion in the Amcbe may assume, interchangeably with the 
common amebal form directly developed in cultivations of 
sporangia in cow dung. In showing this they also afforded a 
ready explanation of the extreme frequency of the parasite in 
the human subject, for they indicated the presence of a constant 
source of readily transferable reproductive elements. 
IV.—Relation of the Excretal Parasites of the Lower Animals 
to those of the Human Subject. 
We have already seen that the vaccine excreta furnish the 
conditions for the continued existence and repeated reproductive 
multiplication of the parasites external to the host-body, crops of 
