678 THE POPULAR SCIENCE MONTHLY, 



the evolution of intellect and the evolution of tactual appendages go 

 hand in hand. In the most intelligent anthropoid apes we find the 

 tactual range and delicacy greatlj^ augmented, new avenues of knowl- 

 edge being thus opened to the animal. Man crowns the edifice here, 

 not only in virtue of his own manipulatory power, but through the 

 enormous extension of his range of experience, by the invention of in- 

 struments of precision, which serve as supplemental senses and supple- 

 mental limbs. The reciprocal action of these is finely described and 

 illustrated. That chastened intellectual emotion to which I have re- 

 ferred in connection with Mr. Darwin is, I should say, not absent in 

 Mr. Spencer. His illustrations possess at times exceeding vividness 

 and force, and from his style on such occasions it is to be inferred that 

 the ganglia of this apostle of the understanding are sometimes the seat 

 of a nascent poetic thrill. 



It is a fact of supreme importance that actions, the performance 

 of which at first requires even painful efibrt and deliberation, may, by 

 habit, be rendered automatic. Witness the slow learning of its letters 

 by a child, and the subsequent facility of reading in a man, when each 

 group of letters which forms a word is instantly and without efibrt 

 fused to a single perception. Instance the billiard-player, whose mus- 

 cles of hand and eye, when he reaches the perfection of his art, are un- 

 consciously coordinated. Instance the musician, who, by practice, is 

 enabled to fuse a multitude of arrangements, auditory, tactual, and 

 muscular, into a process of automatic manipulation. Combining such 

 facts with the* doctrine of hereditary transmission, we reach a theory 

 of instinct. A chick, after coming out of the Q^g^ balances itself cor- 

 rectly, runs about, picks up food, thus showing that it possesses a 

 power of directing its movements to definite ends. How did the chick 

 learn this very complex coordination of eye, muscles, and beak ? It 

 has not been individually taught ; its personal experience is 7iil ; but 

 it has the benefit of ancestral experience. In its inherited organiza- 

 tion are registered all the powers which it displays at birth. So also 

 as regards the instinct of the hive-bee already referred to. The dis- 

 tance at which the insects stand apart when they sweep their hemi- 

 spheres and build their cells is " organically remembered." Man also 

 carries with him the physical texture of his ancestry, as well as the in- 

 herited intellect bound up with it. The defects of intelligence during 

 infancy and youth are probably less due to a lack of individual expe- 

 rience than to the fact that in early life the cerebral organization is 

 still incomplete. The period necessary for completion varies with the 

 race, and with the individual. As a round shot outstrips a rifled one 

 on quitting the muzzle of the gun, so the lower race in childhood may 

 outstrip the higher. But the higher eventually overtakes the lower, 

 and surpasses it in range. As regards individuals, we do not always 

 find the precocity of youth prolonged to mental power in maturity ; 

 while the dullness of boyhood is sometimes strikingly contrasted with 



