218 D, D. CUNNINGHAM, 
active bacteria have been asserted not to be present within the 
intestinal canal. In certain portions, at all events, of the intes- 
tinal canal they are almost invariably present in great numbers 
in an active condition, and the belief that an incapacity for 
movements prevents their entrance into the system, therefore, 
falls to the ground. 
Even where present in great numbers and extreme activity, a 
total disappearance of movement in the bacteria coincides with 
the development of acid coincident with the appearance of 
Oidium. Only when the latter has matured, and coincidently 
with the appearance of alkalinity, do active bacteria again present 
themselves. When once they begin to appear, however, their 
development goes on with intense activity, and quickly runs 
through its various stages to the formation of the so-called 
“ spores.” 
The ameebal organisms occurring in the excreta remain to be 
considered. Like the zoospores, they occur in the excreta 
during health, as well as in cases of cholera and other morbid 
conditions affecting the intestinal canal. Their presence seems 
to be determined by the same conditions as those regulating the 
presence of the zoospores; only, due to the readiness with 
Fig. 4.—Encysted excretal Ameba x 1000. 
which they assume an encysted condition, and thereby are 
enabled to resist the influence of detrimental conditions (Fig. 4) 
they may possibly be rather more constantly detected in one or 
other form than the other bodies are. Owing to their having 
assumed an encysted state, they may be recognised in media 
where they could not maintain activity, and even for considerable 
periods in such as have proved fatal to them, the strong capsule 
of the cyst preventing the content-protoplasm from undergoing 
disintegration for some time after its vitality has been destroyed. 
Due to this, in examining excreta for amebal organisms, we 
must be prepared to recognise both still and active conditions, 
and in regard to bodies representing the former, it is necessary 
to guard carefully against mistaking them for oily particles, or 
vice versa. 
In both theactive and encysted condition they exhibit great varia- 
tions in size, the variation in this respect being specially marked 
in active specimens, asin different media and at different times in 
the same one they not only seem to vary in absolute bulk, due to 
