II Oct., r909.] SJicrry : I fs M aknig a)id Rcariii^s:^. 629 



The relative properties of Mycoderma aceti (the vinegar ferment) and 

 M. villi (flowers of wine) are dealt with at length by Pasteur whose descrip- 

 tion on page 103, Etudes sur le vinaigre, throws mueh light on the subject. 

 Should Mvcoderma vini develop exclusively no harm is done to the result- 

 ing wine — its presence prevents the develojjment of Mycoderma aceti, and 

 causes the wine to remain sound. The plate (adapted from Pasteur's 

 \\ork on vinegar) will enable an idea to be formed of the appearances of 

 these two organisms so widely different in the products they give rise to, as 

 well as in their appearance under the microscope. 



Strange to say, Mycoderma vini has, since Pasteur's remarkable studies, 

 received but little attention at the hands of authorities on wine-making. 

 In French viticultural literature it ligures as a di.sease organism, being 

 incapable of doing much harm, it is usually dismissed wath brief attention. 

 Writers upon the subject consider it powerless to do harm. It is held to 

 turn the alcohol of the wine into water and carbonic acid and the onlv 

 effect it is said to have on the wine is to give it a flat taste {gout d' event). 

 Such action is in marked contrast with the action of the flor film present 

 in Jerez and the extraordinary transformation it brings about in flavour and 

 character of the wine. Such contrast prompts one to ask if the flor film of 

 Jerez is reallv the same organism as the ordinary flo'wers of wine, or if it 

 be an entirely different organism. At the present moment, this question 

 cannot lit- properly decided. 



Pasteur and other writers admit that there are several different varieties 

 of Mycoderma vini. It is highly probable, therefore, in \iew of the very 

 special flavour developed ,by the organism in the bodegas of Jerez, that it 

 is a special varietv which constitutes the film on the fino soleras — a special 

 variety, however, of the ordinary M vcoderma vini which is influenced in the 

 same way bv the same variation in the conditions under which it grows as 

 the common form studied by Pasteur. 



Pasteur's memoir on Acetic Fermentation throws so much light on the 

 relative action of the two organisms and on their behaviour, when lioth 

 are present at the same time, that those interested in this little studied 

 question are referred to it, especially to paragraph IX. on Mycoderma 

 aceti considered as a parasite on Mycoderma vini. After dealing wdth the 

 results of the simultaneous presence of the two organisms in the same 

 liquid, he points out how, in certain cases, the M. vini can decompose the 

 acetic acid produced by M . aceti so that the percentage of acid in the 

 liquid may not increase. He concludes in the following terms : — ■ 



" As soon as, by any circumstance whatever, Mycoderma vini, so frequently 

 (present) on the surface of fermented Hquids when they are exposed to air, happens 

 to lose its vitality, if, for example, food suitable to it is missing, mycoderma aceti 

 invades it after the manner of a parasite living on it and alongside of it, assimi- 

 lating its substances, burning a portion of them bv reason of the same faculty which 

 makes of this Mycoderma an agent of partial or total combustion of alcohol and of 

 acetic acid."* 



This throws light on facts that had been obser^■ed since earliest an- 

 tiquity. 



He quotes Pliny as proof that even ancient writers had given this in- 

 teresting question attention. Plinv says : — 



" White flowers of wine are a good omen, red a bad, unless that be the colour 

 of the wine." 



* Pasteur remarks, in a footnote (p. 23): "The physical aspect of the flowers (film) changes witli 

 its purity, and one can, as it were, connect this aspect with its nature and its action on tlie wine." 



