INTRO D UCTOR Y 1 7 



While the evidence does not have that highest degree of value 

 which I find in my own feelings, good common sense seems to 

 demand that the burden of proof fall on those who hold that 

 apes and dogs and elephants are not rational. 



"Who," asks Agassiz, "is the investigator, who having once 

 recognized such a similarity between certain faculties of man and 

 those of the higher animals, can feel prepared, in the present 

 stage of our knowledge, to trace the limit where this community 

 of nature ceases ? " 



As for myself, I try to treat all living things, plants as well 

 as animals, as if they may have some small part of a sensitive 

 life like my own, although I know nothing about the presence or 

 absence of sense in most living things ; and am no more prepared 

 to make a negative than a positive statement. While it is non- 

 sense to regard trees and rocks and lakes as endowed with mind, 

 it is nonsense because we know nothing about it, and not because 

 it is untrue ; for it is no less nonsense to assert that stones are 

 unconscious than to assert that they are conscious. 



Morgan says ("Habit and Intelligence," p. 41), "To some 

 chicks I threw cinnabar larvae, distasteful caterpillars conspicuous 

 by alternating rings of black and golden yellow. They were seized 

 at once, but dropped uninjured; the chicks wiped their bills a 

 sign of distaste and . seldom touched the caterpillars a second 

 time. The cinnabar larvae were then removed, and thrown in 

 again towards the close of the day. Some of the chicks tried 

 them once, but they were soon left. The next day the young 

 birds were given brown loopers and green cabbage-moth cater- 

 pillars. These were approached with some suspicion, but pres- 

 ently one chick ran off with a looper, and was followed by others, 

 one of which stole and ate it. In a few minutes all the cater- 

 pillars were cleared off. Later in the day they were given some 

 more of these edible caterpillars, which they ate freely ; and then 

 some cinnabar larvae. One chick ran, but checked himself, and, 

 without touching the caterpillar, wiped his bill a memory of the 

 nasty taste being apparently suggested at the sight of the yellow 

 and black caterpillar; another seized one and dropped it at once. 

 A third subsequently approached a cinnabar as it crawled along, 

 gave the danger note, and ran off. Then I threw in more edible 

 c 



