372 



GENERAL PHYSIOLOGY 



metabolism split up grape-sugar into carbonic acid and alcohol, be 

 placed in two fermentation -tubes (Fig. 164), one of which contains 

 a pure solution of grape-sugar, the other some chloroform-water 

 mixed with a similar solution of grape-sugar, there appears at 

 once, under otherwise completely identical conditions, in the first 

 tube a fermentation, as is evident from the carbonic acid rising 

 and accumulating above (Fig. 164, A), but in the second tube an 

 entire absence of fermentation (Fig. 164, B). If the contents of 

 the second tube be left open to the air for a time, so that the 

 chloroform evaporates, fermentation appears there later. The 

 chloroform-water, therefore, only inhibits the metabolism of the 

 yeast-cells without killing them. 



In plant-cells also the depression of metabolism is very easily 

 brought about, especially the cessation of the cleavage of carbonic 



Fig, 164.— Fermentation experiment. A, Produc- 

 tion of carbonic acid in a solution of grape- 

 sugar by means of yeast-cells. B, The solution 

 of grape-sugar is not fermenting because the 

 yeast-cells are narcotised by chloroform-water. 



Fig. leS.—Spirogyra, a filose Alga. 

 A, Piece of a thread conaistuQg 

 of many cells arranged in a row. 

 £, Single cell with the character- 

 istic spiral band of chlorophyll 

 and the star-shaped protoplasmic 

 body. 



acid in chlorophyll. Claude Bernard employed for this a filose, 

 aquatic Alga, Spirogyra, the cylindrical cells of which are arranged 

 lengthwise one after another in fine threads and possess a delicate, 

 spirally wound band of chlorophyll (Fig. 165). Under two' 

 bell-jars, of which one was filled with water containing carbonic 

 acid, the other with water containing carbonic acid and chloroform, 

 he placed a quantity of Spirogyra threads and exposed the jar to 

 the sunlight. After some time the cells in the first jar had evolved 

 a considerable quantity of oxygen, while in the second the evolu- 

 tion of oxygen and, therefore, the dissociation of carbonic acid, were 

 wholly absent. 



Corresponding with the cessation of metabolism, the phenomena 



