t
stars may be decomposed into hydrogen, the latter "element" itself being
also doubtless a compound, which might be resolved under yet more trying
conditions.

Here, then, was what might be termed direct experimental evidence for
the hypothesis of Prout. Unfortunately, however, it is evidence of a
kind which only a few experts are competent to discuss--so very delicate
a matter is the spectral analysis of the stars. What is still more
unfortunate, the experts do not agree among themselves as to the
validity of Professor Lockyer's conclusions. Some, like Professor
Crookes, have accepted them with acclaim, hailing Lockyer as "the
Darwin of the inorganic world," while others have sought a different
explanation of the facts he brings forward. As yet it cannot be said
that the controversy has been brought to final settlement. Still, it is
hardly to be doubted that now, since the periodic law has seemed to
join hands with the spectroscope, a belief in the compound nature of the
so-called elements is rapidly gaining ground among chemists. More and
more general becomes the belief that the Daltonian atom is really a
compound radical, and that back of the seeming diversity of the alleged
elements is a single form of primordial matter. Indeed, in very recent
months, direct experimental evidence for this view has at last come to
hand, through the study of radio-active substances. In a later chapter
we shall have occasion to inquire how this came about.

IV. ANATOMY AND PHYSIOLOGY IN THE EIGHTEENTH CENTURY

ALBRECHT VON HALLER

An epoch in physiology was made in the eighteenth century by the genius
and efforts of Albrecht von Haller (1708-1777), of Berne, who is perhaps
as worthy of the title "The Great" as any philosopher who has been
so christened by his contemporaries since the time of Hippocrates.
Celebrated as a physician, he was proficient in various fields, being
equally famed in his own time as poet, botanist, and statesman, and
dividing his attention between art and science.

As a child Haller was so sickly that he was unable to amuse himself with
the sports and games common to boys of his age, and so passed most of
his time poring over books. When ten years of age he began writing poems
in Latin and German, and at fifteen entered the University of Tubingen.
At seventeen he wrote learned articles in opposition to certain accepted
doctrines, and at nineteen he received his degree of doctor. Soon after
this he vi