404 Canadian Record of Science 



and never secreted a wall and this stage was immedi- 

 ately followed by the disintegration of the whole fila- 

 ment. It was remarkable that in the large amount of 

 Spirogyra collected during October none was found in 

 a fruiting condition, nor were any spores observed. 

 This material was watched carefully throughout the win- 

 ter in the hope that conjugation might take place later 

 on. By placing filaments in various culture media, 

 attempts were made to induce conjugation by arti- 

 ficial means, but none gave the slightest success. Dis- 

 tilled water proved distinctly toxic, causing plas- 

 molysis and death. Neither a two nor a four per cent. 

 Knop's solution had any effect. Both a five per cent, 

 and a one per cent, solution of ammonium nitrate were 

 tried, and appeared only to accelerate the death 

 of the filaments. In a culture of Desmids, on 

 the contrary, the five per cent, solution caused 

 luxuriant growth. In the majority of those cul- 

 tures which contained nothing but Spirogyra, the 

 plants had died by the end of March. 

 On the other hand, in aquaria where there was a 

 large number of forms associated, growth at this time 

 was becoming more and more luxuriant. Quantities 

 of (Edogonium, Chsetophora and Stigeoclonium, some 

 Anabama and a little Spirogyra began to appear to- 

 wards the end of this month. Vaucheria resisted 

 comparatively well the disadvantages of growth under 

 artificial conditions, and was found throughout the 

 winter in various stages of development. Desmids and 

 members of the Protococcaceae occurred in all the 

 aquaria, the varieties of Scenodesmus being especially 

 plentiful. A number of Diatoms were found either 

 floating in chains or attached to filaments of Clado- 

 phora and Vaucheria. They were most abundant 

 at a low temperature. 



An aquarium containing a number of Cyanophyceae 

 collected from the floor of the Conservatory at Mount 

 Royal Cemetery, showed an interesting development. 



