278 PROFESSOR, LANKESTER. 



and such observation was sufficient to satisfy the author, that 

 butyric fermentation was taking place. 



The experiments on the influence of the length of the time 

 of heating on Bacteria showed that — 



(a) Heating for twenty-five hours at 40° was not suifi- 

 cient to kill them; but the delay in commencing to increase 

 in number which was observed when they were placed in the 

 warm-chamber, showed that they had suffered from heat- 

 rigor. 



(j3) Thirteen to fourteen hours' heating at a mean tem- 

 perature of 46°, or 



(y) Three hours at 51° was sufficient to kill them. 



But if Bacterium termo be exposed to a temperature of 

 50° C. in the dry, it still retains its vital activity even if the 

 experiment be continued for as much as six hours, (lower 

 temperatures such as 15° to 16° continued for a Aveek did not 

 destroy the Bacteria) ; such an experiment would tend to 

 show that the surrounding membrane must be of consider- 

 able value, as a protector to the protoplasm within. 



Finally, glass rods that had been dipped in a fluid con- 

 taining Bacteria, and then dried for an hour at 15° C. were 

 brought for a moment in contact with ammonia, alcohol, 

 crude carbolic acid, and acetic acid ; and again dried for 

 an hour in the air ; the only liquid that proved fatal was the 

 last. 



Eidam concludes by insisting on a careful and continuous 

 study of the varying conditions of life, which obtain among 

 the Bacteria. 



Note 07i Bacterium rubescens and Clathrocystis roseo- 

 PERsiciNA. By Professor Lankester, F.R.S. 



I am continually examining new and varied growths of 

 Bacterium rubescens, and the more I see of it, the more I am 

 convinced that Professor Cohn's separation of it into the 

 various species of Clathrocystis and Monas is altogether 

 untenable. I have before me whilst writing this a rich 

 growth which has the characteristic redder tint (not the 

 bluer peach variety) of Bacterio-purpurin. This growth 

 consists of a dense mass of red-coloured Vibrio of the typical 

 form. I consider it to be like the red-coloured Spirillum 

 described by Dr. Klein in this Journal, October, 1875, and 

 the Ophidomonas sanguinea of Ehrenberg — a form -phase of 

 Bacterium, rubescens. 



