CHEMICAL SCIENCE. 183 



"In every case in -which animal or vegetable matter undergoes 

 spontaneous alteration and develops fetid gases, putrefaction is said to 

 occur. We shall perceive in the course of our examination that this 

 definition has two opposite defects. It is too general, because it brings 

 together phenomena that are essentially distinct ; and it is too restricted, 

 because it separates others which have the same nature and origin. 

 The interest and utility of an exact study of putrefaction has never 

 been misunderstood. Long ago it was hoped it might lead to practical 

 consequences in the treatment of maladies which the old physicians 

 termed putrid. Unfortunately the disgust inseparable from labors of 

 this kind, joined to their evident complication, has hitherto arrested 

 the majority of experimenters, so that nearly everything has still to be 

 done. My researches on fermentation have naturally conducted me 

 toward this study; and to the general conclusion that putrefaction is 

 determined by organic ferments of the genus vibrio. 



" The conditions under which putrefaction is manifested may vary 

 considerably. Suppose, in the first instance, the case of a liquid, that 

 is to say of a putrescible substance, of which all the parts have been 

 exposed to contact with the air. Either this liquid may be shut up in 

 a close vessel, or it may be placed in an open vessel, having an aper- 

 ture more or less large. I will examine in succession what happens in 

 the two cases. 



" It is commonly known that putrefaction takes a certain time to 

 manifest itself, and that this time varies according to temperature, 

 neutrality, acidity, or alkalinity of the liquid. Under the most favor- 

 able circumstances a minimum of about twenty-four hours is necessary 

 before the phenomenon begins to be manifested by external signs. 

 During this first period the liquid is agitated by an internal movement, 

 the effect of which is to deprive of its oxygen the air which is in solu- 

 tion, and to replace it by carbonic acid gas. The total disappearance 

 of the oxygen when the liquid is neutral or slightly alkaline is due, in 

 general, to the development of the smallest of the infusoria, the Monas 

 crepusculum and Bacterium termo. A very slight agitation occurs as 

 these little beings travel in all directions. When this first action of 

 exhausting the oxygen in solution is accomplished, they perish and fall 

 to the bottom of the vessel like a precipitate ; and if by chance the 

 liquid contains no fecund germs of the ferments I have spoken of, it 

 remains indefinitely in this condition without putrefaction without 

 fermenting in any way. This is rare, but I have met with several ex- 

 amples. Most frequently when the oxygen in solution has disappeared, 

 the vibrion-ferments, which have no need of this gas, begin to appear, 

 and putrefaction immediately sets in. Gradually it accelerates itself, 

 following the progressive march of the development of the vibrions. 

 The putridity becomes so intense that the microscopic examination of 

 a single drop is very unpleasant. The fetid odor depends chiefly on 

 the proportion of sulphur the substance contains. The odor is scarcely 

 sensible if the matter is not sulphuretted, as, for example, in the fer- 

 mentation of the albumenoid matter which water can carry away from 

 the yeast of beer. The same is the case w r ith butyric fermentation ; 

 and after my experiments butyric fermentation must, from the nature 

 of its ferment, be considered as a phenomenon of exacth r the same or- 

 der as putrefaction properly so-called. Thus we see what happens 



