116 ON THE LATEST FORM OF THE DEVELOPMENT THEORY. 
plate in zoólogy is to be filled up by innumerable transitional forms, is certainly the 
shortest which geology has revealed. As the most recent, also, it is one the history of 
which is most perfectly known. During this period, certainly, it is in the highest de- 
“gree improbable that innumerable species should have lived and died out without 
leaving behind them any trace of their existence. The few fossil monkeys that have 
been discovered are not so near approximations to the human form as several anthro- 
poid species that are now living. How, then, can man have been developed during ` 
this short epoch, by the indefinitely slow process of Cumulative Variation and Natural 
Selection, out of a monkey? and where are the countless extinct types that should 
mark the steps of his progress? How many varieties must have existed as strict 
transitional forms to fill up this broad gap, — to say nothing of the greater, infinitely 
greater number of variations which were not improvements, but which must also have 
appeared and died out under a liability to change having no direction or purpose but 
that of chance! Geology can find no traces of them. The latest chapter of the Stone 
Book, which is far the best preserved, and which ought to be nearly filled with varia- 
tions upon this single theme, does not record a single form intermediate between man 
and the chimpanzee. | : j 
. Moreover, if reason has been diaii dul £ of instinct, these innumerable forms be- 
tween the Quadrumana and the Bimana must have had an enormous advantage in the 
. Struggle for Life over their less intelligent competitors, so that the total disappearance 
of their remains becomes still more inexplicable. Bones of their brute contem poraries, 
hyenas, bears, rhinoceroses, elephants, and even a few monkeys, are found by the 
cart-load in many localities. But a crowd of half-reasoning animals, developed out of 
orangs, chimpanzees, or gorillas, furnished with tools and weapons, and capable, if we 
may judge from their other semi-human attributes, of adapting themselves to a wide 
. range of circumstances, and which ought, consequently, to have multiplied without 
stint, because they were sure to triumph over their brute rivals in every contest for 
the ground or for food, have yet perished so entirely, that not a vestige of their 
skeletons has been anywhere discovered. 
The doctrine that reason has been developed out of instinct, dais adimi upon 
the assumption that these two faculties differ from each other in degree only, and not 
in kind. If psychology is to be placed upon a new foundation, as Mr. Darwin assures 
us, *that of the necessary acquirement of each mental power and capacity by grada- 
tion," there must be a conceivable transition from instinct to reason through a number 
of steps, every one of which must be an improvement. Here we are at once met by the 
difficulty, that the power of instinct, in many cases, quite transcends that of reason; if — 
