C. A. WATKINS ON YEAST AND OTHER FERMENTS. 1G1 



the fluid was covered with a thin film, which proved to he entirely 

 these organisms packed closely together, so that no motion could be 

 seen until some distilled water was added, when their activity was 

 fully displayed. In the course of a few days the film had become 

 a thick viscid scum, consisting entirely of these minute bodies 

 without a sign of any fungoid growth. 



From the fact that these organisms grow most rapidly, and are 

 in the greatest activity at the surface, it appears that air is neces- 

 sary to produce these results, for in the mixture of milk and chalk 

 from which carbonic acid was given off as the lactate of lime was 

 formed, they were always in smaller quantity, and less active con- 

 dition : this vessel, too, was covered with a plate of glass, while all 

 the other solutions were covered with paper. 



When starch or sugar is transformed* into butyric acid, Vibriones 

 are sure to be found in the fluid, whether they produce this fermen- 

 tation or not ; and lately a most remarkable statement has been 

 published by M. Bechamps regarding this matter. This gentle- 

 man asserts that he has discovered that there exist at the present 

 time, in large blocks of chalk taken from a depth of 200 feet from 

 the surface of the soil from a tunnel driven in a mountain, large 

 quantities of microscopic animalculas, which he has named Micro- 

 zyma Cetas ; and he also states that if some of this chalk be placed 

 in a saccharine solution lactic and butyric acid fermentation 

 ensue. 



Yeast is so well known that its description here is quite unneces- 

 sary, and the fact that it converts sugar into alcohol is patent to 

 all. The chemical formula of this change is thus : — 



Grape Sugar. Alcohol. Carbonic Acid. 



CHO = 2CHO +4CO 

 12 12 12 4 6 2 2 



Yeast is supposed to be the conidial condition of Penicillium 

 Glaucum, but much light is required to be thrown on this matter to 

 raise it from its present obscurity. 



The yeast cells consist of an outer membrane of cellulin — the 



* During the transformations which took place in these experiments, I detected 

 no organism having the slightest resemblance to Yeast ; the only fungus being 

 Oidium Lactis, which does not grow in the fluid, and, in my opinion, has no 

 reference to the fermentation. In all the instances in which lactic acid was 

 formed, I noticed only Bacteria or Vibriones, and while I admit that under 

 more favourable conditions of temperature, other growths may appear, I do 

 not consider any of these organisms to be the specific lactic acid ferment. 



