260 D. D, CUNNINGHAM, 
The number of zoospores which may be detected in this way 
is in many cases very remarkable. The size of individual speci- 
mens varies much, which is no doubt greatly dependent on the 
frequency with which processes of division recur in them. Very 
often they measure about 10 y in length by 5 or 6 w in breadth. 
The number of flagella with which they are provided also varies 
from one to three or four; whilst in full activity, neither nucleus 
nor contractile vesicle can be detected as a rule, and after treat- 
ment with Liquor Iodi they may or may not exhibit a nucleoloid 
particle. The latter reagent generally induces a peculiar series 
of phenomena. ‘The body gradually loses its natural fusiform, 
or pear-shaped outline, and becomes circular and motionless. 
Shortly after it has ceased to move, a large vesicular protrusion 
is emitted at one or other point from the somewhat granular 
body, and general disintegration soon sets in. ‘There is no evi- 
dence of any differentiated surface layer, and the flagella appear 
to be merely transitory and changeable protrusions of the pro- 
toplasm. The point opposite to the flagellar site seems to be 
that through which nutritive materials are absorbed, the body 
becoming attached to foreign particles by it, and being some- 
times drawn out in consequence into a caudal process or filament 
of variable magnitude. Allthe characters which the zoospores 
here present are, in short, identical with those occurring in the 
human parasite. The processes of multiplication are also simi- 
lar, consisting in transverse division preceded by diminution or 
temporary arrestin activity, and the phenomena attending dim- 
inished vitality and disintegrative disappearance follow the same 
course. 
While, however, the human and vaccine parasites appear to be 
identical in nature, their presence in the excreta is followed by 
different results. In the case of the human parasites we have 
already seen that a rapid and complete process of destruction 
sets in coincident with the changes normally occurring in their 
medium after its exit from the body, but this does not hold 
good inthe case of the vaccine parasite. That it does not is 
probably due to the absence of any fermentive change in the 
medium corresponding with the acid development coincident with 
the appearance of Oidiwm. In place of disappearing from 
the medium the organisms in the cow dung, after continuing to 
multiply by division for some time, seem to pass on to further 
stages of development through which they are enabled to give 
origin to reproductive bodies providing for the perpetuation 
and diffusion of the species, or where conditions are unsuited to 
this, to resting forms capable of renewed activity on again en- 
countering favorable conditions. The fully developed repro- 
ductive bodies consist of the sporangia, which have been 
