MICROBES, OR BACTERIA. 113 



the end of six months, and is as fit for food as freshly 

 killed meat. 



However this may be, meat which is high is 

 usually not injurious, while putrefied meat produces 

 diarrhoea or still more serious illness. Davaine has 

 shown that the septic properties of decomposed blood 

 are not removed by subjecting it to a temperature 

 of 100, which destroys the microbes, but not their 

 germs or spores; for the destruction of the latter a 

 still higher temperature is necessary. 



For a long while it was believed that the putrefac- 

 tion of dead bodies, and of albuminoid substances, 

 either animal or vegetable, which have been exposed 

 to a moist air at a temperature of from 15 to 30, was 

 merely due to the instability of the organic compounds; 

 these, when left to themselves, tend, under the influence 

 of oxygen, to produce more stable compounds by dis- 

 integration and successive oxidations. Pasteur has, 

 however, shown that in this case also there is a true 

 fermentation; that is, a decomposition produced by 

 the vital action of certain microbes. 



In general, when organic animal substances are 

 exposed to the air, they are in the first instance 

 rapidly covered with moulds; they lose their co- 

 herence, and after the lapse of a few days give off 

 fetid effluvia. Carbonic acid, nitrogen, hydrogen, 

 carburetted, sulphuretted, and phosphoretted hydro- 

 gens, are freely disengaged, and at the same time they 

 combine with the oxygen of the air. The microbes, 



I 



