270 D. D. CUNNINGHAM. 
seems to be preceded by a disappearance of the nucleoli of the 
parent bodies, resulting, apparently, as some cases seem to show, 
from a process of repeated binary division (Pl. X VIII, fig. 11). 
As the sporangia mature and dry the spores lose their spherical 
form, a condensation of their substance seems to take place, and 
they become biconcave; when in this condition they closely 
resemble mammalian. red blood-corpuscles, and, indeed, in many 
cases can hardly be distinguished when mingled with human 
blood. When in this state the margins measure about 2°7 » and 
the central portions about 2°3 » in thickness, the margin being 
of a faint greenish tint, and the centre almost colourless 
(Pl. XVIII, fig. 7). No evidence of the presence of a nucleus 
is, as a rule, present in such spores. 
When a mature sporangium containing such biconcave spores 
is introduced into a suitable medium, the former very rapidly 
swell out and become spherical, and by their increased bulk 
exert a constantly increasing tension on the sporangial wall. The 
capsule ultimately ruptures at one or more points and contracts, 
forcing the spores out in streams and masses into the fluid 
(Pl. XVIII, fig. 2). Where the capsule has disintegrated and 
disappeared the process of swelling up is accompanied by curious 
writhing movements of the spore masses. A contractile vesicle 
soon makes its appearance in the spherical spores, which now, 
as a rule, show a clear central nuclear area surrounded by finely- 
clouded substance, and sometimes apparently containing a 
nucleolar particle of a greenish colour (Pl. XVIII, fig. 8 a). 
After the contractile vesicle has continued to pulsate for a short 
time the body begins to emit a delicate protrusion, and rapidly 
unfolds into a minute Amebula, which crawls freely in the 
medium (Pl. XVIII, fig. 8 4, ¢, fig. 9). In many cases no evi- 
dence of any cyst is left behind, but in others, specially where 
the spores are derived from sporangia which have been sub- 
jected to prolonged desiccation, such a structure is present, 
appearing in the form of a delicate ring after the inmate has 
escaped. The spores then, as a rule, give origin to minute 
Amebe, but, in certain cases, in place of doing so, they appear 
to be resolved into flagellate zoospores, which swim off actively 
in the fluid. 
The assumption of activity by the sporoids is manifestly 
influenced, both by the nature of the fluids into which they are 
introduced, and by the conditions to which they have previously 
been exposed. When introduced into ordinary pure or distilled 
water they remain unaltered for prolonged periods, and either 
fail entirely or in greater part to become active. A momentary 
exposure to the influence of boiling water, as by dropping the 
fluid on sporangia situated on a slide, does not prevent the sub- 
