214 PASTEUR, ON NUTRITION OF THE MUCEDINE^. 



selves on tlie surface of the liquid and there fructify. The 

 vegetation exhibits no symptoms of languor. By taking the 

 precaution of employing an acid salt of ammonia, the deve- 

 lopment of infusoria is prevented, the presence of which would 

 soon arrest the progress of the little plant, owing to their 

 absorption of the oxygen of the air (contained in the water), 

 and which is indispensable to the well-being of the fungus. 

 The whole of the carbon of the plant is dei-ived from the 

 sugar, its azote from the ammonia, and its mineral elements 

 from the phosphates. As regards, therefore, the assimilation 

 of the azote and phosphates, a complete analogy exists be- 

 tween ferments, the mucedines, and plants of a more compli- 

 cated organization. And that this is the case, is further 

 proved in the most decisive way by the following facts. 



If, in the experiment above related, any one of the soluble 

 elements is suppressed, the vegetation is arrested. For ex- 

 ample : the mineral matter is that which would seem to be 

 the least indispensable f"or organisms of such a nature ; but if 

 the liquid contain no phosphates, vegetation is no longer pos- 

 sible, whatever may be the proportion of sugar and ammoniacal 

 salt. All that can be said is, that the germination of the 

 spores may just commence under the influence of the phos- 

 phates contained in the spores themselves in infinitely minute 

 quantity. In the same way, if the ammoniacal salt is sup- 

 pressed, the plant is not developed at all. There is merely 

 the abortive commencement of germination, due to the pre- 

 sence of the albuminoid matter in the spores, although there 

 may be a superabundance of free azote in the surrounding 

 air, or in solution in the liquid. Lastly, the same result fol- 

 lows if the sugar or carbonaceous aliment is absent, notwith- 

 standing there may be any amount of carbonic acid in the 

 air or in the liquid. The author has ascertained a fact, that, 

 as regards the origin of their carbon, the mucedines differ 

 essentially from phanerogamic plants. They do not decom- 

 pose carbonic acid, nor do they evolve oxygen. On the con- 

 trary, the absorption of oxygen and the evolution of carbonic 

 acid are necessary and permanent acts of their vitality. 



What, then, are the consequences of the results of expe- 

 riments above stated ? In the first place, they afford precise 

 ideas respecting the mode of nutrition of the mucedinous 

 fungi, with regard to which science possessed only the ob- 

 servation of M. Bineau, refuted to the Academy by M. Bous- 

 singault on a previous occasion.^ Secondly — and this is^ 



* The interesting experiments of M. Bineau show that the nitrates and the 

 ammonia disappear from the rain-water in which they were held in solution, 

 under the influence of cryptogamic vegetation. It is well known that rain- 



