NOTES ON SOME CANADIAN INFUSORIA. 301 
Many data, however, are yet required to elucidate the action of 
external conditions on these low forms, and my professional] duties 
have not allowed of a sufficient inquiry into the subject to permit of 
any generalizatious or instances being given here. 
In the following notes I do not pretend to give a complete list of 
all the forms observed, but shall merely deal with certain. forms 
which seem to merit description. In the first place, however, it will 
be well to record the general zoological and botanical characters of 
the water. 
As to the vegetable life observed, there was in the first place 
always a large quantity of a small species of Nostoc, apparently N- 
lichenoides, var. vesicarium, usually mucous or hollow in the interior, 
the threads traversing the cavity being surrounded each with its own 
gelatinous envelope. Oscillatorie, Spirogyra, Protococeus and vari- 
ous forms of Chroococcacee were also present in considerable abun- 
dance, although towards the last the Spirogyra threads disappeared. 
Diatoms—principally Vavicula sp.? and Desmids belonging to the 
genera Cosmarium, Closterium, Scenedesmus and Ankistrodesmus 
were exceedingly numerous, and like the Vosfoc were apparently not 
at all affected by cold. Latterly many Bacteria, Baciili and Spirilla 
were present, and in regard to the latter I noticed, that when only a 
small portion of the slide was kept illuminated for a length of time, 
by the use of a diaphragm with a small aperture, they invariably 
congregated in large numbers at that spot, apparently showing that 
these low forms have appreciation of light. Engelmann, however, 
shows ! that these forms only approach the light for the purpose of 
obtaining oxygen, which, under its influence, is given off from green 
algae, etc., only two bacterial forms being observed by him, which 
are attracted to the light for the light’s sake—Bacterium chlorinum, 
which is of a green colour, and B. photometricum, slightly reddish in 
colour. 
As to the animal life, in addition to Infusoria, many lower and 
higher forms were present. When first procured the water contained 
numbers of specimens of Daphnia pulex, De Geer, in company with 
which were an undetermined Ostracode, and Cyclops quadricornis. 
Of these the two former soon disappeared completely, the Cyclops 
disappearing when the water was exposed to a moderately low tem- 
1 Revue Internat. Sci. Biol. ix., 1882. Cf. Journ. Roy. Mier. Soe. ii., 1882. 
