PROTOPLASM AND LIFE. 743 



showed during this time no disposition to germinate. They were not 

 killed, however, they only slept ; for, on the substitution of common 

 air for the etherized air with which they had been surrounded, germi- 

 nation at once set in and proceeded with activity. 



Experiments were also made on that function of plants by which 

 they absorb carbonic acid and exhale oxygen, and which, as we have 

 already seen, is carried on through the agency of the green protoplasm 

 or chlorophyl, under the influence of light a function which is com- 

 monly, but erroneously, called the respiration of plants. 



Aquatic plants afford the most convenient subjects for such experi- 

 ments. If one of these be placed in a jar of water holding ether or 

 chloroform in solution, and a bell-glass be placed over the submerged 

 plant, we shall find that the plant no longer absorbs carbonic acid or 

 emits oxygen. It remains, however, quite green and healthy. In 

 order to awaken the plant, it is only necessary to place it in non- 

 etherized water, when it will begin once more to absorb carbonic acid, 

 and exhale oxygen under the influence of sunlight. 



The same great physiologist has also investigated the action of 

 anaesthetics on fermentation. It is well known that alcoholic fermen- 

 tation is due to the presence of a minute fungus, the yeast-fungus, the 

 living protoplasm of whose cells has the property of separating solu- 

 tions of sugar into alcohol, which remains in the liquid, and carbonic 

 acid, which escapes into the air. 



Now, if the yeast-plant be placed along with sugar in etherized 

 water, it will no longer act as a ferment. It is anassthesiated, and can 

 not respond to the stimulus which, under ordinary circumstances, it 

 would find in the presence of the sugar. If, now, it be placed on a 

 filter, and the ether washed completely away, it will, on restoration to 

 a saccharine liquid, soon resume its duty of separating the sugar into 

 alcohol and carbonic acid. 



Claude Bernard has further palled attention to a very significant 

 fact which is observable in this experiment. While the proper alco- 

 holic fermentation is entirely arrested by the etherization of the yeast- 

 plant, there still goes on in the saccharine solution a curious chemical 

 change, the cane-sugar of the solution being converted into grape-sugar, 

 a substance identical in its chemical composition with the cane-sugar, 

 but different in its molecular constitution. Now, it is well known 

 from the researches of Berthelot that this conversion of cane-sugar 

 into grape-sugar is due to a peculiar inversive ferment, which, while 

 it accompanies the living yeast-plant, is itself soluble and destitute of 

 life. Indeed, it has been shown that, in its natural conditions, the 

 yeast-fungus is unable of itself to assimilate cane-sugar, and that, in 

 order that this may be brought into a state fitted for the nutrition of 

 the fungus, it must be first digested and converted into grape-sugar, 

 exactly as happens in our own digestive organs. To quote Claude 

 Bernard's graphic account : " The fungus ferment has thus beside it 



