ntil they were
revived and extended by Fechner and brought before the world in the
famous work on psycho-physics. Then they precipitated a veritable
melee. Fechner had not alone verified the earlier results (with certain
limitations not essential to the present consideration), but had
invented new methods of making similar tests, and had reduced the whole
question to mathematical treatment. He pronounced Weber's discovery
the fundamental law of psycho-physics. In honor of the discoverer,
he christened it Weber's Law. He clothed the law in words and in
mathematical formulae, and, so to say, launched it full tilt at the
heads of the psychological world. It made a fine commotion, be assured,
for it was the first widely heralded bulletin of the new psychology
in its march upon the strongholds of the time-honored metaphysics. The
accomplishments of the microscopists and the nerve physiologists had
been but preliminary--mere border skirmishes of uncertain import. But
here was proof that the iconoclastic movement meant to invade the very
heart of the sacred territory of mind--a territory from which tangible
objective fact had been supposed to be forever barred.

PHYSIOLOGICAL PSYCHOLOGY

Hardly had the alarm been sounded, however, before a new movement was
made. While Fechner's book was fresh from the press, steps were being
taken to extend the methods of the physicist in yet another way to
the intimate processes of the mind. As Helmholtz had shown the rate of
nervous impulsion along the nerve tract to be measurable, it was
now sought to measure also the time required for the central nervous
mechanism to perform its work of receiving a message and sending out
a response. This was coming down to the very threshold of mind. The
attempt was first made by Professor Donders in 1861, but definitive
results were only obtained after many years of experiment on the part
of a host of observers. The chief of these, and the man who has stood
in the forefront of the new movement and has been its recognized leader
throughout the remainder of the century, is Dr. Wilhelm Wundt, of
Leipzig.

The task was not easy, but, in the long run, it was accomplished. Not
alone was it shown that the nerve centre requires a measurable time for
its operations, but much was learned as to conditions that modify this
time. Thus it was found that different persons vary in the rate of their
central nervous activity--which explained the "personal equation" t