PASTEUR ON FERMENTATION. 717 



gen, all the oxygen of the original sugar, are now in suspension in the 

 air in the gaseous state, ready to be borne away by the winds -and 

 again to enter into the cycle of life under the influence of the benefi- 

 cent heat of the sun. It is here that I would place the providential 

 idea, not sentimentally only, this time, but by a real and serious scien- 

 tific deduction, and because it seems to me that we have seized one of 

 the great laws of Nature. 



Let us return a little upon our steps and see where we are. "What 

 is the condition of our liquid mass ? It is now only water holding in 

 solution a very small quantity of mineral or organic substances. 

 Evajjoration would promptly reduce the whole mass to the deposit of 

 which I spoke a moment ago, and which is lying at the bottom of the 

 vessel, the wine-yeast, the vinegar-yeast in two portions, that which 

 formed the vinegar and that which destroyed it, together with the 

 stems and skins of the grapes. 



What is going to take place in this liquid mass, no longer acid, but 

 neutral now, in which there is held in solution only a little mineral 

 and nitrogenized matter, which, it is true, is always ready to be re- 

 newed, at least for a long time, by the help of the materials at the bot- 

 tom, which, thus far, have undergone nothing but simple maceration ? 



Pressed for time, I was only able at our last meeting to begin 

 my answer to M. Bouillaud, and to do that even in terms so far re- 

 moved from the subject that you must have found it difficult to under- 

 stand the connection of the phenomena then described with the real 

 object of the question. This connection, prepared by what has pre- 

 ceded, will now seem very clear. 



Have we not reached a point in the succession of the grand natural 

 phenomena which I am passing in review, at which we have to deal 

 with a liquid of absolutely the same kind as that which I showed you 

 at our last meeting, and one which is even more suitable for the phe- 

 nomena of putrefaction of which I then spoke ? If the liquid of our 

 great reservoir is now formed of distilled water, phosphates, chlorides, 

 and sulphates, there is at the bottom, to replace the lactate of lime of 

 last Tuesday's experiment, a collection of carbonized or nitrogenized 

 substances much better fitted than lactic acid to supply the carbonic 

 food suitable for the development of the vibrios. 



And, in fact, scarcely has the last mycodermic pellicle fallen to the 

 bottom, scarcely have a new death and a new quiet fallen upon our 

 liquid, scarcely has it lost all acidity, when, little by little, it becomes 

 cloudy throughout ; germs floating in the air have brought to it a new 

 life, not one like those which you have seen precede it, but another, 

 one rendered possible by the neutral character of the new liquid. The 

 whole surface becomes covered by a layer of fatty, mucilaginous as- 

 pect. In the deeper portions, throughout the whole mass, as I said, 

 we see a milky cloudiness ; at the same time an infectious and very 

 deleterious odor announces, even at a distance, the putrefaction and 



