426 Canadian Record of Science 



NOTE. 



By periodically renewing the water in Miss Miller's 

 aquaria, so as to prevent the undue concentration of the 

 mineral contents and by guarding against excessive ex- 

 posure to strong light, many of the cultures were kept 

 in good condition, during the summer of 1912, and 

 furnished excellent material for class-work throughout 

 the following winter. Towards the spring of 1913, hardy 

 forms like Scenodesmus crowded out less resistive genera 

 and the cultures were allowed to die during the summer. 



Similar cultures started in October, 1913, were com- 

 paratively unsuccessful, the summer having been un- 

 favorable to the majority of the groups. Spirogyra, 

 Zygnema, Mougeotia, CEdogoniums and several of the 

 Protococcacege began to grow after a few weeks. In 

 December, practically all were attacked by disease, 

 bacilli, vibrios, spirilla and water moulds abounding 

 in the aquaria. These conditions were probably due in 

 part to the high temperature which was maintained in 

 the laboratories, in 1913-14, possibly in part to a less 

 rigorous use of hypochlorite of lime in connection with 

 the water- works of the city. 



Miss Miller's results show that where water-supplies 

 are freed from deleterious bacteria, a luxuriant develop- 

 ment of algae will cause pollution unless preventive 

 measures, such as treatment with copper sulphate, are 

 taken. 



C. M- D. 



January, 1915. 



