STUDIES ON FERMENTATION. 109 



of the oxygen necessary to the activity of this growth, and the 

 heat developed in the film, as well as the liberation of carbonic 

 acid gas, that result from it are considerable. A piece of glass 

 covering the mycoderma, at some distance above it, becomes wet 

 with moisture, that soon accumulates to form large drops of 

 water. The quantity of oxygen absorbed is so great that we 

 never see any other fungoid growth on the surface of this film, 

 although the air is constantly depositing on it, as dust, spores of 

 an entirely diflferent character ; for, notwithstanding that the 

 warm and moist surface is in contact with an atmosphere 

 that is being continually renewed, yet the mycoderma ap- 

 propriates to itself all the oxygen contained in the air. 

 When, however, the vegetation begins to languish, we often 

 find, on the other hand, that the plant becomes associated 

 with other species of mycoderma, notably mycoderma aceti, 

 as well as other fungi, amongst which 2)eniciUium glaucrim 

 generally appears. This is one of the facts which, wrongly 

 interpreted, have led to the belief that mycoderma vini or 

 ceremdce may possibly, or even readily, become transformed into 

 innicillium, and vice versa* As the study of the growth of 



* Since writing this paragraph, we have found in M. Ch. Eobin's 

 Journal cTAnatomie. et de Physiologie, an article signed by that gentleman, 

 and entitled Sur la Nature cles Fermentations, &c. (July-August, 1875), in 

 which the learned microscopist says: — "The torula cerevisice is derived 

 from the mycoderma cerevisice. My observations leave no doubt on my 

 mind that penicilliuin glaucum is one of the forms evolved from spores 

 or ferments that have preceded it, as M. Trecul showed a long time ago, 

 and that, moreover, the spores of peniciUium, germinating in suitable 

 media, give us the sporical form termed mycoderma.'" 



We take the liberty to observe that these assertions of M. Eobin's are 

 purely gratuitous. Up to the present time it has been impossible to 

 discover a suitable medium for the proof of these different transforma- 

 tions or polymorphisms. From the time of Turpin, who firmly believed 

 that he had observed these changes, to our own, none of the micro- 

 scopists who have affirmed these transformations have succeeded in 

 adducing any convincing proof of them, and M. Trecul's latest observa- 

 tions, especially as regards penicillium and its transformation into 

 ferment or into the mycoderma of beer, have been positively disproved by 

 ours, supported, as they are, by proofs that we consider irrefutable. 



