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The Germ Theory and its 
[December, 
At the risk of some hard words we must endeavour to 
combat this kind of opinion, and to show the world that 
germs are in no sense to be laughed at, but that an insight 
into their nature and their actions would conduce greatly to 
our well-being. 
What, then, is a germ ? A microscopic being, in some 
cases of animal, but more commonly of vegetable nature. 
More strictly speaking, a germ is the egg or seed of such 
minute creatures. These germs are suspended in the air, 
scattered over the earth, over vegetation, and over animals, 
heing in fa(5t almost omnipresent. Such germs differ in their 
nature, and accordingly they produce very different effects. 
If one of them falls into any suitable liquid,— be it blood, 
milk, grape juice, &c., — or upon any solid organic matter, 
such as the flesh of a dead animal, it becomes developed, 
and reproduces its like with great rapidity. In so doing it 
effects most important changes in the matter which it inha- 
bits. Thus suppose we crush a quantity of grapes, and 
leave their juice exposed to the air, in a short time the juice 
undergoes that change which is known as alcoholic fermenta- 
tion. The sugar present in the juice is decomposed, forming 
carbonic acid, which escapes, and alcohol, which remains in 
the liquid ; this change is effected by a minute plant, a.Saccha- 
romyces. In its absence neither wine, beer, nor any alcoholic 
liquid can originate fermentation, as has been experi- 
mentally proved. Under certain conditions, further, if wine 
or beer is exposed to the air, we know that it passes into 
vinegar. This is the action of a “ germ ” of another kind. 
In a precisely similar manner the putrefaction of milk, of 
flesh, &c., is occasioned by other “ germs.” If these are 
absolutely excluded, as in a tin of Australian meat, no pu- 
trefaction sets in, and the meat may be preserved for an 
indefinite time. We may easily learn that it is not the 
previous boiling which keeps the meat from entering into 
decomposition, for if we make a small hole into such a tin, so 
as to admit the air, the meat in a short time becomes 
offensive. It might be argued that the air itself, indepen- 
dent of any germs which it may convey, occasions fer- 
mentation and putrefaction ; but this supposition is at once 
overthrown by the faCt that if air is admitted which has 
been passed, e.g., over red-hot asbestos or pumice-stone in 
a glass tube, or which has been filtered through cotton-wool, 
no fermentation or putrefaction arises. On this subject the 
beautiful experiments of M. Pasteur and of Prof. Tyndall 
may be regarded as conclusive. 
But certain germs are capable, under favourable circum- 
