MICROBES, OR BACTERIA. 118 
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, 
