GROWTH OF FUNGI AND OF INFUSORIA. 331 



freshly drawn into perfectly pure vessels behaved in an exactly 

 similar manner. When a little putrefying urine was added to 

 the fresh urine, the putrefaction o^ the latter was accelerated in 

 a high degree. Wood, in which urine had been retained, ex- 

 erted this action in a very decided manner, and the white, or 

 yellowish-white deposit from putrefying urine (which does not 

 possess an organized form) effects the conversion of urea into 

 carbonate of ammonia in the course of a few hours. 



Fresh flesh remains for several weeks without experiencing 

 appreciable change in a perfectly pure glass vessel, whether the 

 latter contains common air, or air previously heated to redness : 

 but, at the same time, it absorbs oxygen, and emits carbonic acid, 

 and passes into putrefaction, if the necessary quantity of water 

 be present, the process not being prevented or retarded by the ig- 

 nition of the air. 



It cannot be supposed, that dung- flies, living upon animal ex- 

 crements, are the cause of this putrefaction ; neither can a similar 

 conclusion be drawn in the case of mites and maggots found so 

 abundantly in old cheese. 



When we consider, that the intermediate products formed in 

 the passage of animal and vegetable matters into inorganic com- 

 pounds possess the power of supporting the life of certain ani- 

 mals and vegetables low in the scale of creation, then the only 

 mystery is, in what manner the germs of the fungi, or the eggs 

 of the infusoria, reach ihe place fitted for their development ; for 

 this being known, there is no difficulty since the discoveries of 

 Ehrenberg, in conceiving this extraordinary increase. Now, as 

 it is observed that the infusoria increase in size only to a certain 

 point, it must hence be concluded that their nourishment, even if 

 only from the point at which they are to grow, passes out of their 

 bodies in the form of excrements, precisely as in the higher order 

 of animals. As in the case with all other excrements, these 

 must possess, in an eminent degree, the property of passing into 

 decay or putrefaction ; and this condition must at all events be 

 induced by contact, with the original putrefying body. Hence 

 the increase in numbers of the" infusoria must induce and acce- 

 lerate the process of putrefaction in the putrefying body itself. 

 The ultimate products of decay and putrefaction are carbonic 



