Fresh-water Algce of Canada. 837 



lowest forms of animal life. The phenomenon of the aggregation 

 of sporules, or the granular contents of filaments or cells, which 

 is so marked a feature in most of the confervoid plants, is one that 

 admits of still further investigatiou than it has yet received. We 

 have been tempted to think, from various appearances which we 

 have observed in several species of Algse, that this aggregation 

 may be found referrible to some general principle, peculiar to fer- 

 ilized zoospores whose escape is retarded by the cell walls within 

 which they are germinated. The subject is, however, a difficult 

 one. The objects to be examined are so minute, that to observe 

 their developement under the microscope, is all but impossible. 

 The evidence upon which a determination must mainly rest, will 

 be of a negative character, and only appreciable by those who 

 have given the subject attentive study. In a future paper we 

 hope to direct special attention to this point. 



The Vaucherise possess the remarkable property of resisting the 

 action of severe cold for a lengthened time. We collected some 

 specimens this spring, immediately after the dissolving of the ice, 

 in a pond the water of which had been frozen into a solid mass for at 

 least four months and a half. Many of the plants had shed their 

 spores, but others were quite fresh and healthy. Autumn would 

 appear to be the time during which they are chiefly to be found 

 in a perfect state. They may, however, be found in shady and 

 damp ditches during spring and summer. 



We have been able to determine the following species : — 

 I. Vaucheria dichotoma, Ag. 



Char. — Frond setaceous dichotomous, fastigiate. Vesicles solitary 



globose sessile, Grev. 

 Hab. — In ponds and ditches ; frequent ; annual ;_ spring and sum, 

 mer. In the fields at Mile End Toil-Bar, Montreal. 

 Hassall's Hist. Brit. F. Algce, p. 51, Plate IV., fig. 1. 

 Hassall doubts if this species is anything more than a condi- 

 tion of V. sessilis. The capsules are the same in both. A yel- 

 lowish or olive green is the color of all this genus when aged or 

 in seed. 



II. V. Geminata, Vauck. 

 Char. — Capsules situated on the peduncle common to both. An- 

 ther intermediate. 



TlassalPs Hist. Brit, F. Algce, p. 55, Plate III, fig. 1. 

 This belongs to a subdivision of the genus in which the vesicles 



