Fresh Water Algae in Vicinity of Montreal ±09 



Reproduction takes place ordinarily in the vernal 

 phase. They consider it to be the result of certain 

 periodically recurring combinations of factors which 

 vary for different species. The nature of the stimulus 

 causing reproduction is, therefore, an intensification of 

 these conditions which is liable to occur in spring. 

 Such intensification taking place at other times in the 

 year would lead to exceptional cases of reproduction. 



In a study of this nature, it is out of the question to 

 attempt to confirm either the theory of Copeland that 

 conjugation results from internal rather than from ex- 

 ternal conditions, or that of Fritsch that conjugation 

 results from a periodically recurring combination of 

 external factors. However, the appearance of numerous 

 species of Spirogyra in October, and the entire absence 

 of any fruiting material at that time, as well as my 

 failure to obtain any conjunction in the laboratory dur- 

 ing the winter, incline me to believe that while certain 

 conditions of light, temperature and density of 

 water, as Fritsch suggests, probably induce the 

 second appearance of Spirogyra in the fall, conjuga- 

 tion results from certain periodically recurring in- 

 ternal conditions. 



The Formation of Ehizoids in Spirogyra. 



An interesting development was observed in an 

 aquarium containing Spirogyra fluviatilis Hilse, col- 

 lected from one of the quarry holes in Amherst Park. 

 This vessel contained a large amount of the alga and, 

 in examining some of the filaments in January, it was 

 observed that at the end of many there was an abnor- 

 mal growth. The end cell seemed to have lost most of 

 its chlorophyll, the characteristic spiral chromatophore 

 was broken up, and the cell had branched into two or 

 more narrow root-like prolongations. Further search 

 revealed filaments in all stages, from an almost 



