213 



Researches on the Mode of Nutrition of the MucedinejE. 



By M. L. Pasteur. 



(' Comptes rendus,' vol. li, p. 709.) 



About eighteen months since the author communicated to 

 the Academy an experiment on the subject of yeast, which 

 attracted the particular attention of physiologists. When an 

 almost imponderable trace of the yeast-fungus was sown in 

 pure water, holding in solution certain crystallizable and, as 

 it may be said, inorganic principles — that is to say, sugar- 

 candj'^, an ammoniacal salt, and some phosphates — the minute 

 globules of the yeast-fungus might be seen to multiply, pro- 

 curing their azote from the ammoniacal salt, their carbon 

 from the sugar, and their miueral constituents from the phos- 

 phates, the sugar at the same time undergoing fermentation. 

 The absence of any one of the three aliments prevented the de- 

 velopment of the yeast. Subsequently, M. Pasteur extended 

 his researches, with the same result, to the lactic ferment. 



The above experiment was conclusive as to the organized 

 nature of beer-yeast, which Berzelius, even in his latest writ- 

 ings, always regarded as a chemical precipitate of a globular 

 form. It moreover afforded a manifest proof of the concealed 

 relations which exist between the ferments and the higher 

 plants. 



All the previous labours of the author, communicated to 

 the Academy for some years past, concur in the establishing 

 of the principle, that all fermentations have their origin in 

 mycodermic plants occupying the lowest place in the scale of 

 being. The result of the author's more recent researches 

 now made public will add a new support to this opinion. 

 Taken with the results of his former experiments on the sub- 

 ject of yeast, they will show a great analogy between ferments 

 and the lowest as well as the highest forms of plants. The 

 author, consequently, hopes that physiologists will find in 

 similar researches a new method of inquiry opened to them, 

 fitted for the rigorous and easy examination of various ques- 

 tions respecting the nutrition of plants. 



In pure distilled water he dissolves an acid, crystallized 

 ammoniacal salt, some sugar-candy, and the phosphatic salts 

 procured by the incineration of yeast. He then sows in the 

 liquid some spores of Penicillium, or any mucedinous fungus; 

 These spores readily germinate, and in a short time (only two 

 or three days) the liquid is filled with flocculi of the mycelium 

 of the fungus, of which a great many quickly spread them- 



