Mr. W. K. Sullivan on the nature of Lactic Fermentation. 209 



showing that yeast can be rapidly formed in a solution of pure 

 sugar if a salt of ammonia and phosphates be added. On trying 

 the same experiment with lactic yeast, he produced a perfectly 

 healthy lactic fermentation with a deposition of yeast-globules. 



In my paper " On the presence of Ammonia and Nitric Acid in 

 the Sap of Plants*," I dwelt upon the probability that plants derive 

 the whole of their nitrogen from ammonia. There is nothing 

 more natural, therefore, than that the yeast plant should be able 

 to develope itself when provided with its proper food. But if 

 the single cell constituting the yeast plant be capable of assimi- 

 lating ammonia and building up out of it albuminous bodies, is 

 it likely that it would also possess the power of assimilating all the 

 wide range of substances in all stages of alteration, which go by 

 the name of albuminous bodies? The cell-wall of all the ferment 

 plants is cellulose ; and yet one species produces vinegar, another 

 alcohol and carbonic acid, and another lactic acid, — a diffei-ence 

 of function which we can scarcely find between single cells even 

 in the higher families of plants, where every cell may be said to 

 enjoy a different chemical and physiological function. It seems 

 more probable to suppose that azotic matter, in an active state, 

 gives off ammonia (Schmidt showed that ammonia existed in 

 fermenting liquorst),and that as the spores of fungi abound every- 

 where, they at once grow and multiply, wherever the ammonia is 

 thus given off, because there their proper supply of food exists. 

 We know that even the diffusion of a solution of a salt into pure 

 water is enough to produce a certain amount of decomposition : 

 how much more so must this be the case during the exosmosis 

 and endosmosis of complex and therefore unstable substances 

 already in a state of activity, through the cellulose membrane of 

 the yeast-cells. The primum movens may therefore be, as Liebig 

 supposes, an azotic body in a state of change, the yeast-cells 

 growing upon the products of decomposition, and therefore re- 

 moving them from the field, while the flow of liquids through 

 the cell presents greater facilities for decomposition by molecular 

 action. According to this view, vegetation is not the primum 

 movens, but the consequence of fermentation. 



Pasteur states that the origin of the lactic fermentation, in the 

 experiments which he made, was solely due to atmospheric air. 

 In the case of the milk examined by me, air could not have 

 assisted, as it was wholly excluded. It may no doubt be ob- 

 jected that the milk contained some air when it was introduced 

 into the bottle. I grant it; but why did the lactic fermentation 

 not set in at the usual time, and not after a considerable period, 



* Atlantis, vol. i. p. 41.'S; and Aiiaalcs tie VlUsloire Nutitrclle for 

 February 1850. 



t Annul. d;r Cliem, uud Phnrm. vol. Ixi. j). 1(58. 



P/dl. Mag. S. 4. Vol. 18. No. 111). Sept. 1859. P 



