24 report — 1879. 



The same great physiologist has also investigated the action of anaes- 

 thetics on fermentation. It is well known that alcoholic fermentation is 

 due to the presence of a minute fungus, the yeast fungus, the living 

 protoplasm of whose cells has the property of separating solutions 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 etherised water 

 it will no longer act as a ferment. It is anaesthesiated, and cannot re- 

 spond 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 called attention to a very significant fact 

 which is observable in this experiment. While the proper alcoholic 

 fermentation is entirely arrested by the etherisation 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 Bertholet 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 in the same yeast a sort of 

 servant given by nature to effect this digestion. The servant is the 

 unorganised inversive ferment. This ferment is soluble, and as it is not a 

 plant, but an unorganised body destitute of sensibility, it has not gone to 

 sleep under the action of the ether, and thus continues to fulfil its task.' 



In the experiment already recorded on the germination of seeds the 

 interest is by no means confined to that which attaches itself to the arrest 

 of the organising functions of the seed, those namely which manifest 

 themselves in the development of the radicle and plumule and other organs 

 of the young plant. Another phenomenon of great significance becomes 

 at the same time apparent — the anaesthetic exerts no action on the concom- 

 itant chemical phenomena which in germinating seeds show themselves 

 in the transformation of starch into sugar under the influence of diastase 

 (a soluble and non-living ferment which also exists in the seed), and the 

 absorption of oxygen with the exhalation of carbonic acid. These go on 

 as usual, the anaesthesiated seed continuing to respire, as proved by the 

 accumulation of carbonic acid in the surrounding air. The presence of 

 the carbonic acid was rendered evident by placing in the same vessel 



