[300] 
NOTES ON 
SOME CANADIAN INFUSORIA. 
BY J. PLAYFAIR McMURRICH, M.A., 
Professor of Biology in the Ontario Agricultural College. 
For some weeks past I have been occupied in identifying some 
Infusoria found in water from a pool in the neighbourhood of the 
Ontario Agricultural College, Guelph. This was obtained during 
the past summer, and has been standing in a moderately warm spot 
since. Even during the time I have been engaged in investigating 
it, its fauna has varied considerably, depending, to a certain extent 
at least, on the temperature, which has been allowed to vacillate 
within somewhat wide limits. A lowering of temperature will no 
doubt cause the disappearance of certain forms, whereby other more 
hardy ones, in the struggle for existence, will, by obtaining more 
abundant food be able to propagate themselves, and hence appear 
more abundantly, and also no doubt it will act indirectly upon certain 
other forms by destroying their usual food, and thus eventually 
causing these forms to disappear also, although they may of them- 
selves be able to withstand the increased cold. 
The only reference I have been able to find to any researches on 
the influence of low temperature on Infusoria is contained in Semper’s 
work on the Natural Conditions of Existence as they affect Animal 
Life. He there alludes to Rossbach’s investigations as to the influ- 
ence of temperature on the pulsation of the contractile vesicle, which 
show that at 5° c. the contractions follow each other at long intervals, 
and at 3° c¢. a condition supervenes, which Rossbach has termed 
“chillcoma,” from which the animal can be roused by increasing the 
temperature, but if it be long continued at that degree, death super- 
venes. These observations were conducted only with Chilodon cweul- 
lus, Euplotes charon and Stylonychia pustulata, and even in these 
forms considerable variation was observed. 
