SECT. in. FERMENTS. 289 



of the Uredines segetum and Rosse,of Ascophora elegans, 

 Mucor Mucedo, Periconia hyalina and others. There 

 are active exchanges continually going on between the 

 contents of the globules of ferments and the exterior 

 liquid, and therefore a continual chemical action. 4 



M. Pasteur's experiments on the nourishment of the 

 Mucedines concur with the observations of others in 

 showing that these plants are the origin of all fermen- 

 tation properly so called. When he put a mere trace 

 of the beer yeast fungus into pure water holding in 

 solution the three crystallizable substances, sugar candy, 

 an ammoniacal salt, and some phosphates, the globules 

 of yeast were seen to multiply, deriving their nitrogen 

 from the ammoniacal salt, their carbon from the sugar, 

 and their mineral material from the phosphates ; at the 

 same time the sugar fermented. The same results 

 were obtained from lactic yeast. M. Pasteur now sowed 

 the spores of the Penicillium, or of some other mucedi- 

 nous fungus in pure distilled water holding in solu- 

 tion the same ingredients, except that an acid salt of 

 ammonia was employed to prevent the development of 

 infusoria, which would soon have stopped the progress 

 of the microscopic plant by absorbing the oxygen with- 

 out which fungi cannot live. The result was the same as 

 in the preceding case. There is consequently a complete 

 analogy between the ferments, the mucedines, and plants 

 of more complex structure. If in these experiments any 

 one of the principles in the solution be omitted, the 

 vegetation is arrested. The quantities of these sub- 

 stances in the air, the water, or in the spores themselves, 

 are not sufficient to make up for the suppression of 

 any one of them. For example, the carbonic acid in the 

 air or water does not make up for the omission of 

 the sugar. The mucedines and fungi generally obtain 

 their carbon from their food and from rain water, for 



4 M. Hoffmann. 

 VOL. I. U 



