it is recalled that all higher intellection must in all probability
involve multitudes of widely scattered centres.

No better explanation was forthcoming, however, until the year 1889,
when of a sudden the mystery was cleared away by a fresh discovery.
Not long before this the Italian histologist Dr. Camille Golgi had
discovered a method of impregnating hardened brain tissues with a
solution of nitrate of silver, with the result of staining the nerve
cells and their processes almost infinitely better than was possible by
the methods of Gerlach, or by any of the multiform methods that other
workers had introduced. Now for the first time it became possible to
trace the cellular prolongations definitely to their termini, for the
finer fibrils had not been rendered visible by any previous method
of treatment. Golgi himself proved that the set of fibrils known as
protoplasmic prolongations terminate by free extremities, and have no
direct connection with any cell save the one from which they spring.
He showed also that the axis cylinders give off multitudes of lateral
branches not hitherto suspected. But here he paused, missing the real
import of the discovery of which he was hard on the track. It remained
for the Spanish histologist Dr. S. Ramon y Cajal to follow up the
investigation by means of an improved application of Golgi's method of
staining, and to demonstrate that the axis cylinders, together with
all their collateral branches, though sometimes extending to a great
distance, yet finally terminate, like the other cell prolongations, in
arborescent fibrils having free extremities. In a word, it was shown
that each central nerve cell, with its fibrillar offshoots, is an
isolated entity. Instead of being in physical connection with a
multitude of other nerve cells, it has no direct physical connection
with any other nerve cell whatever.

When Dr. Cajal announced his discovery, in 1889, his revolutionary
claims not unnaturally amazed the mass of histologists. There were some
few of them, however, who were not quite unprepared for the revelation;
in particular His, who had half suspected the independence of the cells,
because they seemed to develop from dissociated centres; and Forel,
who based a similar suspicion on the fact that he had never been able
actually to trace a fibre from one cell to another. These observers
then came readily to repeat Cajal's experiments. So also did the veteran
histologist Kolliker, and