The works of Lyell put an end to the doctrine
of catastrophism, but other researches have seem
ed to show that though the solar system might re
main, life oi this earth mut have an end.
As is well known, both animals and plants
need certain of the chemical elements as food, in
order to nuintain life, these necessary elements
being carbon, oxygen, hydrogen and nitrogen,
besides others of less importance.
Plants can use these elements for food when
presented in the form of very simple compounds
or even uncombined in the cases of certain of
them. Nitrogen, however, must always be com
bined, to serve as a food, the plant being totally
unable to use any of the vast quantity of this gas
which forms four-fifths of the atmosphere, it there
being uncombined.
With animils the food must contain the same
elements, but combined to form very complex
substances and as these are produced almost ex
clusively by plants in their growth, animals are
directly dependent upon plants for life.
Turning to the sources of plant food we find in
the soil and air an abundant supply of all the ele
ments needed except nitrogen. The element, it
is true, is abundant, but the supply of its com
pounds which the plant requires, is comparatively
limited; those present in all soils forming the
greater portion, the nitrate and guano beds being
far from inexhaustible, and the other sources be
ing few.
Here animals come to the aid of plants, for
among the waste matters produced by animals are
simple nitrogenous compounds which plants can
easily utilize. In this we find a sort of circle of
changes, the simple substances and elements be
ing built up by plants into complex substances
which are used as food animals which in return
supply the plants with waste matters which are
built up again.
This circle of animal and vegetable life might
ever continue, each supplying food to the other,
were it not for one, great difficulty—the waste mat
ter produced by animal life is not all returned to
THE FREE LANCE.
the plants. Particularly is this true in our cities
where the sewage is conveyed . far beyond the
reach of plants—to the sea.
With reference to the other elements this would
matter little, the soil and atmosphere holding an
abundant supply, but with the nitrogenous com
pounds the case is different—-with only a portion
of these returned, and with but a limited supply
in the soil, the time must come when nitrogen
starvation will result in the destruction of all
plants, and in consequence, the total annihilation
oflife on this earth.
This has been the end expected. But recently
science which discovered the inter dependence of
animal and vegetable life has discovered an in
fluence struggling to restore the balance. It has
long been known that land planted with clover,
peas, beans or other leguminous plants, appeared
to lose none of the nitrogen present in the soil.
The reason for this is now known. In the little
swellings so common on the roots of these plants,
swarms of bacteria are actively at work, in some
unexplained way taking the nitrogen from the air
and so making it over that it can be utilized by
the plants which in this manner receive the ele
ment previously lacking.
Bacteria are wonderful agents for good and for
evil. They cause disease, but often supply the
remedy; feeding in marshes and stagnant pools
they render those regions inhabitable when other
wise they would be uninhabitable wastes; they aid
ih the preparation of ou rfood; in cooking and in
digesting it; butter, cheese and many other pro
ducts require their presence to be successfully pro
duced ; and by this study of animal and vegetable
food we see that even the presence of life on this
earth may directly depend on the abundance and
vigor of the bacteria of nitrification.
The grounds and buildings of the colleges in the
United States are valued at $56,119,826, their
productive funds at £60,597,142 and their total
income, including state aid, £8,293,444.