620 VITAL ACTIONS OF THE LOWER FUNGI. 



different to that where the acetic acid is formed by means 

 of spongy platinum; the latter process is increased by an 

 elevation of temperature which is destructive to the fungus. 

 Nevertheless, it is evident that the action as oxygen-carriers 

 must be bound up with a large number of intact fungus-cells, 

 and that this action must, to a certain extent, run" parallel with 

 the active development of the fungus. And further, the fact 

 that specific forms are found in association with the formation 

 of acetic acid can not alter Pasteur's view; for the con- 

 ditions of existence of the fungi which take part in the 

 formation of acetic acid are so peculiar both as regards the 

 amount of alcohol and the amount of acetic acid in the medium, 

 that only few forms can enter into concurrence with them. 

 Whether, however, as a matter of fact, only one or several 

 forms are involved in the action must be determined by 

 further pure cultivations. 



If, on the other hand, the formation of acetic acid is a 

 physiological act of certain fungi, we would expect that the 

 multiplication of the fungi would be intimately connected 

 with their function, that other products of tissue change 

 would also be formed, that, at all events, there must be in 

 part a further oxidation of the acetic acid. And further, it 

 is a question whether we ought in reality to look on the for- 

 mation of acetic acid as a fermentative process, or whether 

 we must not simply regard it in this way that the fungi, 

 among other nutrient materials, also take up alcohol, when it 

 is present in particularly large amount, and oxidise it only to 

 acetic acid. In the latter case Pasteur's carrying of the 

 oxygen takes place in the cells ; the alcohol acts as nutrient 

 material, which, when present in smaller quantity in the 

 nutrient mixture, is destroyed and burned up by very various 

 kinds of fungi ; which, however, when in a more concentrated 

 form only permits the growth of a few fungi, and is then no 

 longer burned up to the usual end products. This oxidation 

 of the alcohol can only be designated as fermentation in the 

 ordinary acceptation of the term, when it has been demon- 

 strated that relatively very large quantities of the material 

 can be acted on in a short time, that almost the whole of the 

 ferment escible material undergoes this incomplete oxidation, 

 and that this metamorphosis of the material is sufficiently 

 different from the ordinary physiological processes to be 

 looked on as a special function, as compared with the as- 

 similatory and destructive tissue change. The solution of 

 these questions must be given by further investigations. If, 

 in reality, we have to do with a fermentation, then the whole 

 process of the acetic fermentation can be best understood on 

 Nageli's theory, to be mentioned immediately. 



