THE METABOLISM OF PLANTS. 



307 



bottle was observed by means of a thermometer introduced through the 

 cork. 



Eriksson also ascertained that Yeast evolves heat in 

 the absence both of oxygen and of alcoholic fermentation. 

 Pasteur has pointed out that Yeast can live upon milk-sugar, 

 though it cannot cause it to ferment, and Eriksson availed 

 himself of this fact for the purpose of his experiments. 



The apparatus was the same as that described above : one of the 

 bottles (A) was filled with small pellets of blotting-paper containing a 

 mass of Yeast moistened with solution of milk-sugar, and the air was 

 removed from the bottle by passing a current of hydrogen through it for 

 half-an-hour ; the other bottle (B} was filled with pellets of moistened 

 blotting-paper. 



It is of interest to note in connexion with the foregoing experiment 

 that the admission of air to the Yeast in the bottle A was immediately 

 followed by a considerable rise of temperature. 



202 



