158 ORGANIC EVOLUTION — MENTAL 



knowledge, small as compared to the acquired knowledge 

 accumulated in subsequent life by such a bird as a 



were nnliooded. Their behaviour, however, was in every case 

 conclusive against the theory that the perceptions of distance and 

 direction by the eye are the result of experience, or of associations 

 formed in the history of each individual life. Often at the end of 

 two minutes they followed with their eyes the movements of 

 crawling insects, turning their heads with all the precision of an 

 old fowl. In from two to fifteen minutes they pecked at some 

 speck or insect, showing not merely an instinctive perception of 

 distance, but an original ability to judge, to measure distance, 

 with something like infallible accuracy. They did not attempt to 

 seize things beyond their reach, as babies are said to grasp at the 

 moon ; and they may be said to have invariably hit the objects at 

 which they struck — they never missed by more than a hair's 

 breadth, and that too when the specks at which they aimed were 

 no bigger, and less visible, than the smallest dot of an i. To seize 

 between the points of the mandibles at the very instant of striking 

 seemed a more difficult operation. I have seen a chicken seize 

 and swallow an insect at the first attempt ; most frequently, how- 

 ever, they struck five or six times ; lifting once or twice before 

 they succeeded in swallowing their first food. The unacquired 

 power of following by sight was very plainly exemplified in the 

 case of a chicken that, after being unhooded, sat complaining and 

 motionless for six minutes, when I placed my hand on it for a few 

 seconds. On removing my hand the chicken immediately followed 

 it by sight backward and forward, and all round the table. To 

 take, by way of example, the observations in a single case a little 

 in detail : — A chicken that had been made the subject of experi- 

 ments on hearing, was unhooded when nearly three days old. 

 For six minutes it sat chirping and looking about it ; at the end of 

 that time it followed with its head and eyes the movements of a fly 

 twelve inches distant ; at ten minutes it made a peck at its own 

 toes, and the next instant it made a vigorous dart at the fly, which 

 had come within reach of its neck, and seized and swallowed it at 

 the first stroke ; for seven minutes it sat calling and looking about 

 it, when a hive bee coming sufficiently near was seized at a dart 

 and thrown some distance, much disabled. For twenty minutes 

 it sat on the spot where its eyes had been unveiled without attempt-' 

 ing to walk a step. It was then placed on rough ground within 

 sight and call of a hen with a brood of its own age. After stand- 

 ing chirping for about a minute it started off towards the hen, dis- 

 playing as keen a perception of the qualities of the outer world as 

 it was ever likely to possess in after life. It never required to 

 knock its head against a stone to discover that there was " no road 

 that way." It leaped over the smaller obstacles that lay in its path 

 and ran round the larger, reaching the mother in as nearly a 

 straight line as the nature of the ground would permit. This, let 



