Fresh Water Algae in Vicinity of Montreal 407 



(Roth) Kiitz was killed when placed in cultures of tap 

 water and distilled water containing NILNO, even when 

 a trace of this salt was added to a nutrient culture of five 

 months' standing. His experiments seem to show 

 clearly that in many cases at least the absence of am- 

 monium salts is not enough to bring about conjugation. 

 These results show considerable similarity to those 

 which were given by my cultures, both in the dele- 

 terious effect of NH4NO3 on 8. setiformis (Roth) 

 Kiitz, and the failure of all artificial methods to induce 

 conjugation. 



Copeland's work consisted in a study of Spirogyra 

 both under natural and artificial environment. In the 

 laboratory, he found that very satisfactory cultures 

 could be made with tap-water, and even a .04 per cent. 

 Knop's solution gave favourable results. But no par- 

 ticular advantage was observed from the use of nutrient 

 solutions. It was noticed that it was a decided 

 advantage to shade the aquaria with dark 

 paper when first started. The good effect was 

 especially noticeable in the south-east windows, where 

 the light was strongest. The proximity of (Edogonium 

 and Chara proved beneficial to Spirogyra, (Edogonium 

 being invariably present and often the predominating 

 form in the aquaria where Spirogyra lived for several 

 months or a year. Oak leaves and charcoal also ap- 

 peared to be beneficial factors. 



In field work he collected thirteen species of Spiro- 

 gyra, of which twelve fruited abundantly. Ten of 

 these passed their period of maximum abundance in 

 May, one in August and one in October. One 

 reliable example of a second fruiting was 8. dubia, 

 which fruited in May and again in July. The period 

 of maximum abundance was proved in every case to 

 correspond with the period of maximum conjugation. 

 After conjugation, the fruiting filaments and the vege- 

 tative forms disappeared at the same time. One 

 species was observed during several years, but never 



