NOTES ON SOME CANADIAN INFUSORIA. 301 



Many data, however, are yet required to elucidate the action, of 

 external conditions ou these low forms, and my professional duties 

 have not allowed of a sufficient inquiry into the subject to permit of 

 any generalizations or instances being given here. 



In the following notes T 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 iV- 

 lichenoides, var. vesicarium, usually mucous or hollow in the interior, 

 the threads traversing the cavity being surrounded each with its own 

 gelatinous envelope. Oscillator ice, Spirogyra, Protococcus and vari- 

 ous forms of Ohroocoecacece were also present in considerable abun- 

 dance, although towards the last the Spirogyra threads disappeared. 

 Diatoms — principally Navicula sp. 1 and Desmids belonging to the 

 genera Cosmarium, Closterium, Scenedesmus and Ankistrodesmus 

 were exceedingly numerous, and like the Nostoc were apparently not 

 at all affected by cold. Latterly many Bacteria, Bacilli 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 l 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 13. 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- 



i Revue Internat. Sci. Biol, ix., 18S2. Cf. Journ. Roy. Mier. Soc. ii., 1882. 



