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NOTES ON 



SOME CANADIAN INFUSOEIA. 



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 Gldlodon cucul- 

 lus, Euplotes charon and Stylonychia piistulata, and even in these 

 forms considerable variation was observed. 



