472 
ent one, that an English surgeon began to 
ponder over a conception which, however, 
he did not make known until some years 
later, and which did not gain complete 
demonstration and full acceptance until 
still more years had passed away. It was 
in 1811, in a tiny pamphlet published pri- 
vately, that Charles Bell put forth his ‘ New 
Idea’ that the nervous system was con- 
structed on the principle that ‘‘the nerves 
are not single nerves possessing various 
powers, but bundles of different nerves, 
whose filaments are united for the conveni- 
ence of distribution, but which are distinct 
in office as they are in origin from the 
brain.” 
Our present knowledge of the nervous 
system is to a large extent only an exem- 
plification and expansion of Charles Bell’s 
‘New Idea,’ and has its origin in that. 
If we pass from the problems of the liv- 
ing organism viewed as a machine, to those 
presented by the varied features of the dif- 
ferent creatures who have lived or who still 
live on the earth, we at once call to mind 
that the middle years of the present cen- 
tury mark an epoch in biologic thought 
such as never came before, for it was then 
that Charles Darwin gave to the world the 
‘Origin of Species.’ 
That work, however, with all the far- 
reaching effects which it has had, could 
have had little or no effect, or, rather, could 
not have come into existence, had not the 
earlier half of the century been in travail 
preparing for its coming. For the germinal 
idea of Darwin appeals, as to witnesses, to 
the results of two lines of biologic investi- 
gation which were almost unknown to the 
men of the eighteenth century. 
To one of these lines I have already re- 
ferred. Darwin, as we know, appealed to 
the geological record; and we also know 
how that record, imperfect as it was then, 
and imperfect as it must always remain, 
has since his time yielded the most striking 
SCIENCE. 
[N. S. Von. X. No. 249. 
proofs of at least one part of his general 
conception. In 1799 there was, as we have 
seen, no geological record at all. 
Of the other line I must say a few words. 
To-day the merest beginner in biologic 
study, or even, that exemplar of acquaint- 
ance without knowledge, the general reader, 
is aware that every living being, even man 
himself, begins its independent existence as 
a tiny ball, of which we can, even acknowl- 
edging to the full the limits of the optical 
analysis at our command, assert with confi- 
dence that in structure, using that word in 
its ordinary sense, it is in all cases abso- 
lutely simple. It is equally well known - 
that the features of form which ‘supply the 
characters of a grown-up living being, all 
the many and varied features of even the 
most complex organism, are reached as the 
goal of a road, at times a long road, of suc- 
cessive changes ; that the life of every being, 
from the ovum to its full estate, is a series 
of shifting scenes, which come and go, 
sometimes changing abruptly, sometimes 
melting the one into the other, like dissolv- 
ing views, all so ordained that often the 
final shape with which the creature seems 
to begin, or is said to begin its life in the 
world is the outcome of many shapes, 
clothed with which it in turn has lived 
many lives before its seeming birth. 
All or nearly all the exact knowledge of 
the labored way in which each living crea- 
ture puts on its proper shape and structure 
is the heritage of the present century. Al- 
though the way in which the chick is 
moulded in the egg was not wholly un- 
known even to the ancients, and in later 
years had been told, first in the sixteenth 
century by Fabricius, then in the seven- 
teeth century in a more clear and striking 
manner by the great Italian naturalist, 
Malpighi, the teaching thus offered had 
been neglected or misinterpreted. At the 
close of the eighteenth century the domi. 
nant view was that in the making of a crea- 
