Fresh Water Algae in Vicinity of Montreal 403 



had begun to disintegrate. Zygnema was also diffi- 

 cult to cultivate. Although in some of the aquaria it 

 continued to live for a couple of months, it had dis- 

 appeared from the majority after about a month. But 

 both Anabasna and Zygnema began to appear in some 

 of the aquaria in March, noticeably in those which 

 contained a number of other types. 



No Mougeotia was observed in the material first 

 collected. But in December, when the temperature of 

 many of the aquaria was allowed to rise considerably, 

 it developed in great quantities in a large number. 

 Ulothrix was noticed early in February in many 

 of the aquaria where it had not been previously 

 observed. Cladophora glomerata (L.) Kiitz, which 

 was growing attached to a stone, lived in a uniformly 

 healthy condition all winter. So did Microsporia cras- 

 sior (Hansg.) Hazen, which seemed to be especially 

 hardy and flourished under every condition of light 

 and temperature. 



One aquarium contained a lump of clay on which a 

 quantity of Stigeoclonium was growing. This began 

 to die down in December and by the beginning of 

 January none was to be found- The lump of 

 clay was then placed in a two per cent. Knop's solu- 

 tion. In four weeks it was covered with a most 

 luxuriant growth of Stigeoclonium. Cladophora also 

 responded promptly to the nutritive effects of Knop's 

 solution. 



Some twenty of the aquaria contained Spirogyra, 

 generally associated with several other genera, but 

 usually forming the bulk of the material in each. 

 When collected, Zygnema andCEdogonium were usu- 

 ally present with Spirogyra, but they soon died out. 

 Spirogyra continued to live for three or four months 

 in a comparatively healthy condition, but after this it 

 showed signs of degeneration, the filaments became 

 etiolated, the cytoplasm broke up into bodies some- 

 what resembling cysts. These were, however, very small 



