BY JAMES TOLSON, ESQ. 73 
decomposition really is. The knowledge of this process, 
usually termed “fermentation” or ‘“ putrefaction,” as the 
case may be, has been developed very greatly of late years, 
and by none to such an extent as by the eminent French 
scientist, Pasteur, whose discoveries in this particular 
branch have excited the admiration of all. As the subject 
is too great to be dealt with in a paper like this, we can 
only glance briefly at its leading features. 
It is now a well ascertained fact that the decomposition 
of organic substances is due to the action of minute living 
organisms, which, penetrating the tissues, increase at an 
enormous rate, at the expense of the substances composing 
the body in which they have effected a lodgment. Experi- 
ment shows that they are to be found almost everywhere 
in the atmosphere, being most numerous in a_ moist 
warm air and proportionately scarce in dry cold regions. 
Heat and moisture are necessary to their existence, 
although a temperature of 160° F. destroys them. At and 
below 32° F. they become dormant, and their vigour increases 
as the temperature rises, until, in the case “of the germs 
producing acid fermentation (v/brios), they arrive at their 
maximum state of energy, at a temperature of from 60° to 
80° F., and, in the case of the germs producing putrid 
fermentation (bacteria),ata temperature al 95: to 105° 
at which point putrid decomposition is most rapidly 
effected. Confining our attention to the changes which 
occur in the case of animal tissues being subjected to the 
action of the vibrios and bacteria, we ‘find, as stated by 
Schutzenberger, that— 
‘Organic matter of animal origin left in contact with air under- 
goes progressive and complex transformations, known under the 
name of putrefaction and of slow combustion, whose effect is to 
transform them into principles more and more simple by means 
of decomposition and oxidation, so that in the end the carbon is 
restored to the air in the form of dioxide, the hydrogen under the 
form of water, and the nitrogen either as free nitrogen or ammonia. 
M. Pasteur has distinguished among the complicated facts of 
putrid fermentation two orders of distinct phenomena, although 
each is connected with the reactions set up by living organisms. 
The first includes the putrefaction which takes place without the 
assistance of oxygen in the air, which is caused by the presence of 
vibrios; the second, slow combustion, is due to the bacteria, 
