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244 NATURE AND LIFE. 
After examining the alterations produced in the living, 
we have to consider those occasioned by fermentations in 
the dead. When life has retreated by slow degrees from all 
the parts of an organized being; when, after all partial 
deaths have occurred, total death has possessed the depths 
of the subject, and broken all the springs of its activity, the 
work of putrefaction begins. Its task is to unmake this 
body, to destroy its forms, and dissever its materials. The 
work to be done is to disorganize it, to reduce it into 
solids, liquids, and gases, fit to go back again into the vast 
reservoir whence new life is incessantly issuing. This is 
the task that heat, moisture, air, and germs, will undertake 
in unison. It is all performed with steady diligence. Na- 
ture knows no delays; as soon as the body is cold, the pro- 
tecting coating that covers all its surface, the epithelium, 
decays in places, particularly in the moister parts. The 
agents of disorganization, vibrios and bacteria, or rather 
the germs of these thread-like corpuscles, penetrate through 
the skin, wind into the small ducts, invade the whole 
blood, and by degrees all the organs.° Soon they swarm 
everywhere, almost as numerous as the chemical molecules 
in the midst of which they stir and circle. The albuminoid 
matters are decomposed into fetid gases, escaping into the 
air. The fixed salts, alkaline and earthy-alkaline, slowly 
release themselves from the organic matters with which 
they combined to form the tissues. The fats oxidize, and 
grow acrid ; the moisture dries away. Every thing volatile 
vanishes, and, at the end of a certain time, nothing remains 
save the skeleton, but a formless mingling of mineral prin- 
ciples, a sort of humus, ready to manure the earth. Now, 
all these complex operations absolutely required the in- 
tervention of the infusoria of putrefaction. In pure air, 
deprived of living germs, they could not have been accom- 
plished. To check putrid fermentations, to insure the con- 
servation of animal or vegetable substances in a state of 
