3'S STUDIES ON FERMENTATION. 



lactic ferment or lactic acid. The whole theory of the transmu- 

 tation of ferments, which M. Duval has published, is imaginary.* 

 We have asserted that the source from which we obtain 

 our supply of the substances that we expose to contact with 

 the air may likewise furnish a reason for the development 

 of vegetable or animal organisms which make their ap- 

 pearance in our infusions. This may be easily under- 

 stood. If we expose the infusions to temperatures more or 

 less high, with the object of destroying the vitality of the 

 germs which they may contain, we completely suppress 

 all germs originating from two different sources — those 

 which the infusions maj^ have acquired directly from the 

 atmospheric air, or from the dust upon our utensils, and those 

 which may have been introduced by the materials used in 

 manufacturing our infusions or decoctions, which materials must 

 have been brought from some distance. An infusion, after 

 having been heated to a sufficient degree, can harbour and 

 nourish only such germs as are conveyed to it by the air after 

 the heating. These floating germs are far from being as varied 

 in their nature as it pleases those to believe who are tied down 

 by their arbitrary and faulty interpretation of the knowledge 

 that we have acquired, and the discussions in which we have 

 taken part, during the last fifteen years. Air, unless in violent 

 agitation, can hold only the most minute particles in suspen- 

 sion. The observations which have been recorded concerning 

 organisms of spontaneous growth found in infusions, have 

 always been made in sheltered places — in rooms or laboratories, 

 the atmosphere of which is, relatively speaking, verj'- still. 

 For this reason, in liquids that have been subjected to heat, 

 the flora and fauna — if we may use such an expression — are 

 very poor, and all the more so because, as we have recently 



• Jules Duval (of Versailles), Nouveaux fails concernant la mutahiUte 

 des germes microscopiques. Role passif des etres classes sous le nom de 

 ferments. (See the Journal d'Anatomie et de Physiologie, edited by C. 

 Robin, Sept. and Oct. 1874, and Compte-rendus de V Acadrmie des Sciences, 

 Nov. 1874). M. Bechamps had previously fallen into similar errors. 



