48 THE ROYAL SOCIETY OF CANADA 



The Behaviour oj Yeast with Methyl-Green 



By W. B. Leaf, B.Sc. 



Presented by Professor W. Lash Miller, F.R.S.C. 



If yeast be planted in wort containing methyl-green it may or 

 may not reproduce, depending on the amount of yeast used and on 

 the concentration of the green. If seeded to a count of 100 (100 X 

 250,000 cells per c.c.) in wort containing 0.167% methyl-green no 

 reproduction takes place; if left in the solution for more than 100 

 hours the cells will still form colonies on wort-agar, but will not form 

 colonies on wort-agar containing 0.005% methyl-green- — a medium 

 on which untreated yeast grows freely. The relation between the 

 duration of "sickening" in the 0,167% green, and the time required 

 to cause active fermentation in pure wort, has been studied ; also the 

 behaviour of the "sickened" yeast with phenol, the acclimatization 

 of yeast to methyl-green, and its reversion when grown in pure wort. 



The Scattering oj Light; Note on Wolski's Paper on Optically Empty 



Liquids 



By Professor F. B. Kenrick, F.R.S.C. 



In Kolloidchemische Beihefte, 13, 137 (1920) P. Wolski describes 

 experiments in which he filters water and other liquids through 

 collodion filters and thus obtains liquids w^hich show no bright specks 

 under the ultramicroscope. In expressing these results, however, he 

 uses language which is capable of a very different interpretation from 

 that which is justified by his experiments. He says that "the water 

 had become completely optically empty" and (in his final con- 

 clusions) "therefore the light specks and scattering phenomena 

 observed up to the present time result from the presence of a foreign 

 substance." In view of these statements it seems necessary once 

 more to make clear that, as found by Martin (1913), the motes in a 

 liquid may be removed by several different methods: distillation 

 without ebullition, cataphoresis, envelopment, and no doubt, also by 

 filtration through collodion, but that there still remains a light- 

 scattering which is constant in intensity irrespective of the method 

 of purification. 



