138 



STUDIES ON FERMENTATION. 



When the buds of the oval or spherical cells detach them- 

 selves whilst young, they often resemble in form and size cells 

 of ordinary j^east, nor can even considerable experience in this 

 kind of observation always enable us to distinguish them. 

 Hence we may easily understand how many have come to 

 believe, with so skilful a botanist as Dr. Bail, in the transforma- 

 tion of mucor into yeast. 



With the forms represented in Plates V. and VI., the plant is 

 more of a ferment than of a fungoid growth. In such cases 

 the weight of sugar decomposed in comparison with the weight 

 of new cell -globules formed is very considerable, an effect 

 which is more marked the less air the plant has at its disposal. 

 Under the latter conditions, however, vegetation is slow and 

 laborious, and the ferment very soon assumes an aspect of age, 

 and we must constantly rejuvenate the cells by bringing them 

 into contact with oxygen, and subjecting them to the action of 

 limited quantities of that gas, and so promote their vegetation 

 and prolong their fermentative activity. This effect we brought 

 about when we retransferred the liquid and its deposit of mucor 

 from the test-glass to the flask, thus bringing them into contact 

 with fresh air. We saw cells that appeared old, dark, and 

 highly granulated, become inflated, grow more transparent, and 

 fill with a gelatinous protoplasm, the few granulations which 

 they still exhibited assuming a brilliant appearance when we 

 succeeded in distinguishing them ; and finally, a very active 

 budding was set up. Under this reviving influence life could 

 continue once more away from the air, although with difficulty, 

 so that fermentation would be most intense if the large fila- 

 ments and their conidia were constantly being removed from 

 and to the action of air. 



The preceding plates show several instances of this rejuvenes- 

 cence of the old cells of mucor ferment. 



We have omitted to represent amongst the old cells some 

 cells which have their granulations collected about the centre, 

 with an empty space between the granulations and the exterior 



