drift-men is almost as absurd as to apply it to the civilized neolithic herdsmen."1

Of the existence of what one might call anteprehistoric men, many are no less certain than if their bones had been discovered; for, as Sir John Lubbock has well said, the question is not whether these men had bones, but whether they actually existed; and that they did exist is amply proved by the rude flakes of flint which they left, as well as by the bones of animals on which the impressions of those flint knives still remain. Yet there are chances that more light may some time be thrown on this difficult subject; for, says Lyell, in closing his great work, "The Antiquity of Man,”

"We have not yet searched those pages of the great book of Nature in which alone we have any right to expect to find records of the missing links alluded to: the countries of the anthropomorphous [man-like] apes are the tropical regions of Africa, and the Islands of Borneo and Sumatra, lands which may be said to be quite unknown in reference to their pliocene 2 and post-pliocene mammalia."

A simple diagram will serve far better than any words to illustrate the enormous lapse of

1 Men who lived just before the historic period, in a time when implements were largely made of polished stone.

2 Belonging to the latter part of the tertiary age.

A. The time from the earliest historical period to the present.

B. Time since the close of the last glacial period.

C. Time since the beginning of the next to the last glacial period. D. Time since the beginning of the tertiary.

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time that separates us from the days of primitive man.

So long as many even who are opposed to the development theory find reason to admit that man may have originated over two and a half million years earlier than the earliest human bones that have yet been identified, we may well believe that the human race has endured long enough for all the development needed to bring some ape-like animal up to the level of the Canstadt race.1

1 The estimate of over two and a half million years, though large, is by no means beyond the figures of the best authorities. Many high authorities are, as already stated, disposed to believe in the existence of the race far back into the tertiary. Croll's estimate, before quoted, is two hundred and forty thousand years for the quaternary age; and Dana makes the tertiary and quaternary together something like three million years. The difference, 2,760,000 years, would stand for the period of development from the time of primitive man to that of the man of the river-drift. Of course no one pretends that such figures as these do any thing more than give us some idea of the relative proportious of the several periods.

CHAPTER X.

HISTORICAL SKETCH.

- CONCLUSIONS.

THE

HE complete history of the growth of the development theory would in itself afford a wonderful illustration of a process of evolution.

Whatever be one's knowledge of botany or zoölogy, whatever be one's bias regarding the application of the theory, one cannot fail to see that the thought of to-day is permeated by the one idea of growth, progress, evolution. That .`thought rules our pursuit of knowledge in all directions, physical, philosophical, ethical.

From the works of Aristotle down to those of the scientists and philosophers of to-day, we find here and there thoughts, suppositions, and conclusions tending towards such an explanation of the organic world as has only been formulated into a working hypothesis since the patient accumulation of facts bearing on the subject was begun by Mr. Darwin, almost half

a century ago. In this place there will only be room for allusion to a very few of the more important steps that have been taken in advancing the theory to its present comprehensiveness.

Herbert Spencer has laid down as a general principle, that the early beliefs of mankind are not usually true beliefs. This is but one special application of the truth, now generally recognized by students of the human race, that man has arisen from an extremely rude and unintelligent condition to the position which he now occupies. The ideas of a savage are no less inferior to our own than are his manners or his morals. And, even long after the savage condition has been left behind, men's conceptions of the laws of nature remain exceedingly imperfect.

Until the eighth century it was universally believed that all substances consisted of earth, air, fire, and water united in various proportions. The circulation of the blood seems to have been merely guessed at, until it was definitely announced by Harvey in 1619; and, up to that time, physiologists in general contentedly acquiesced in the opinion of the ancients, that the blood remains stagnant, or nearly so, throughout the veins. For a long time the arteries were thought to be filled with air. Our