126 STUDIES ON FERMENTATION. 



that just described. We substituted for the test-flask another 

 flask — or, better still, a simple glass tube — containing carbonate 

 of lime that had been subjected to great heat in the flask or 

 tube, and there left to cool down. When cold, we poured the 

 powdered carbonate of lime into the liquid in the flask, in this 

 way avoiding the possibility of any error from the introduction 

 with the carbonate of lime of any foreign germ. 



In neither case did we obtain alcoholic fermentation, nor was 

 there any appearance of lactic fermentation, or bacteria, or 

 vibrios, properly so called. The flasks remained in the oven, at 

 a temperature of about 25° C. (77° F.), until the end of January, 

 1873, when we made a microscopical examination of their 

 deposits, exercising greater care and precaution than we had 

 adopted in the case of those examinations which we had made 

 from time to time in the course of the experiment to assure our- 

 selves of the nature of the organisms present.* The result was 

 that we never found anything besides the mycoderma aceti, 

 which had developed, although with great difficulty, on the sur- 

 face of the liquids neutralized with carbonate of lime. The 

 beaded filaments had, under these circumstances, only become 

 a little larger than they had been in the unsweetened acid 

 liquids. 



Mycoderma aceti, then, grown on sweetened acid or neutral 

 liquids, grown in the absence or in the presence of carbonate of 

 lime, undergoes no transformation into bacteria or vibrios or 

 yeast, if only we operate with pure germs, free from the dust 

 floating in the air, and from that which, unknown to the 

 operator, may be introduced by means of the vessels and 

 materials employed. It may be asked, do we, therefore, abso- 

 lutely, reject the theory of the polymorphism o^ mycoderma aceti ? 



* We need scarcely here observe, having done so on previous occasions, 

 that whenever we opened our flasks to obtain specimens, we made use of 

 a fine tube, previously passed through the flame of a spirit lamp, and 

 that we also passed this flame over the surface of the india-rubber, glass 

 stopper, &c., to consume the organic particles of dust which floating 

 about might introduce themselves at the moment when we opened the 

 riirht-hand tube of the flask. 



