680 
AN ESSAY ON EAT AND MUSCLE. 
sequence of which is, the worms and slush of every description 
which he devours counteract the astringent or tannin principle of 
the acorn, and they thrive amazingly. When the farmers around 
the New Forest feed their swine with acorns in the sty, they in- 
variably give other food mixed with them, such as wash, brewers’ 
grains, potatoes, turnips, beet, and the refuse of the gardens, as 
they find that swine fed on acorns only seldom thrive. 
Our essay is now brought to a close ; and, from what has been 
stated, it must be evident that constant and progressive change 
appears to be one of the leading characteristics of life : the whole 
seems like one vast laboratory, where mechanism is subservient to 
chemistry — where chemistry is the agent of the higher powers of 
vitality. In considering the digestive functions of animals, we 
have seen the manner in which vegetable food is assimilated into 
blood and tissues ; we see that the materials have to pass through a 
great number of intermediate stages before they can attain their 
final state. We can perceive all these; but still we have as yet 
a very imperfect knowledge of the nature of the vital agents con- 
cerned in producing those chemical changes which the food must 
necessarily undergo during its assimilation. The living principle, 
whether of a vegetable or animal, is so adapted that it can elaborate 
its body out of the materials which are around it ; but neither can 
create out of nothing that matter of which its organization, during 
its appointed time, is composed. These materials, but few in 
number, are first elaborated from the air, the earth, and the waters, 
into the substance of plants, for the food of herbivorous and grami- 
nivorous animals, which, in their turn, are eaten by carnivorous 
animals; and when, after a time, the spirit has left its tenement, 
the organized body is resolved into its original inorganic sub- 
stances — carbonic acid, water, and ammonia — these elements being 
either returned to the atmosphere, whence they were derived, or 
imbedded in the parent soil, again to constitute races of vegetables, 
and to contribute to the nourishment of organized beings. Even 
those portions of organic matter which, in course of decomposi- 
tion, escape in form of gases, and are widely diffused through the 
atmosphere, are not wholly lost to living creatures; for, in the course 
of time, they also re-enter into the vegetable kingdom, resuming 
the solid form, and re-appearing in organic products, destined 
again to pass through the same never-ending cycle of vicissitudes 
and transmutations. This is the most important page in the whole 
book of material nature, for thus is grass changed into mutton and 
beef, which afterwards are changed into the flesh of man. 
