e study of the interaction of these
internal secretions, their influence upon development, upon mental
process and upon disorders of metabolism is likely to prove in the
future of a benefit scarcely less remarkable than that which we have
traced in the infectious diseases.

CHEMISTRY

IT is not making too strong a statement to say that the chemistry and
chemical physics of the nineteenth century have revolutionized
the world. It is difficult to realize that Liebig's famous Giessen
laboratory, the first to be opened to students for practical study, was
founded in the year 1825. Boyle, Cavendish, Priestley, Lavoisier, Black,
Dalton and others had laid a broad foundation, and Young, Frauenhofer,
Rumford, Davy, Joule, Faraday, Clerk-Maxwell, Helmholtz and others
built upon that and gave us the new physics and made possible our age
of electricity. New technique and new methods have given a powerful
stimulus to the study of the chemical changes that take place in the
body, which, only a few years ago, were matters largely of speculation.
"Now," in the words of Professor Lee, "we recognize that, with its
living and its non-living substances inextricably intermingled, the
body constitutes an intensive chemical laboratory in which there is ever
occurring a vast congeries of chemical reactions; both constructive and
destructive processes go on; new protoplasm takes the place of old. We
can analyze the income of the body and we can analyze its output, and
from these data we can learn much concerning the body's chemistry. A
great improvement in the method of such work has recently been secured
by the device of inclosing the person who is the subject of the
experiment in a respiration calorimeter. This is an air-tight chamber,
artificially supplied with a constant stream of pure air, and from which
the expired air, laden with the products of respiration, is withdrawn
for purposes of analysis. The subject may remain in the chamber for
days, the composition of all food and all excrete being determined, and
all heat that is given off being measured. Favorable conditions are
thus established for an exact study of many problems of nutrition. The
difficulties increase when we attempt to trace the successive steps in
the corporeal pathway of molecule and atom. Yet these secrets of the
vital process are also gradually being revealed. When we remember that
it is in this very field of nutrition that there exist great popular
ignorance