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THE AMERICAN MUSEUM JOURNAL 



stubbornness. And so the observer 

 gains the feeling that the two organ- 

 isms are quite as different in reactive 

 tendency as are two men. 



It has often been remarked that the 

 individuals of a human race with which 

 one is unfamiliar look alike. This we 

 always discover to be due to our failure 

 to notice marked individual differences. 

 As our familiarity with the type in- 

 creases, these individual traits become 

 increasingly obvious. Xow precisely 

 what is true in our experience with our 

 fellow men is still more true of other 

 types of organism. We note at first 

 only the species or racial differences, or 

 perhaps if they be equally conspicuous, 

 certain age and sex differences, but as 

 we continue to live with the organisms 

 and to observe them carefully day by 

 day, we come to appreciate those quali- 

 tative and quantitative peculiarities 

 which constitute individuality. As far 

 as we can see, there is no significant dif- 

 ference in degree of individuality be- 

 tween earthworm and man, ant and 

 monkey. 



Intimacy of relation with a wide 

 range of organic types has served, 

 among other things, to convince us that 

 temperament, character, and genius are 

 terms, which, like individuality, may 

 be used quite as appropriately in con- 

 nection with one type of organism as 

 with another. We wish especially, in 

 this paper, to report certain of our ob- 

 servations concerning these aspects of 

 life. Temperament we have come to 

 think of as the sum of fundamental, 

 inborn reactive tendencies, — they are 

 sometimes called primary instincts; 

 character, as these same tendencies or- 

 ganized through environmental contact 

 or experience into a complex and more 

 or less highly adaptive system of beha- 

 vior; genius, as exceptionally strong or 

 well-marked temperamental traits of a 



particular order. The conventional 

 and ancient classification of tempera- 

 ments according to strength and dura- 

 tion of response as choleric, melan- 

 cholic, sanguine, and phlegmatic seems 

 unduly simple in the light of our ob- 

 servations, for there are at least several 

 important ingredients or constituents 

 of temperament which apparently vary 

 independently or in groups with respect 

 to strength and duration of response, 

 and possibly also in other important 

 ways. We may not here further dwell 

 upon definitions, but we shall hope to 

 render these suggestions more significant 

 by the facts which we have to record. 



Some years ago we undertook a com- 

 parative study of two strains of albino 

 rat, the one closely inbred for many 

 generations, the other outbred. Save 

 for this difference, the individuals of 

 the strains were entirely comparable. 

 We attempted by various experimental 

 means to discover peculiarities of be- 

 havior in these animals. Soon it be- 

 came apparent that the inbred indi- 

 viduals adapted themselves less readily 

 to new environmental demands. They 

 proved less apt pupils in tests of habit 

 formation. We were struck, as our ob- 

 servations progressed, by certain pecu- 

 liarities of behavior which appeared to 

 be characteristic of the strains rather 

 than of individuals. Among them, 

 fear, timidity, savageness, curiosity, so- 

 ciability were conspicuous. In general, 

 the inbred rats seemed more timid, 

 fearful, more likely to defend them- 

 selves by biting if disturbed, less ready 

 to try new things, more suspicious of 

 the experimenter, slower to acquire ob- 

 viously profitable modes of response 

 than AA'ere the outbred animals. These 

 differences in behavior seemed to us to 

 account for an apparent difference in 

 intelligence, and we finally concluded 

 that it is really quite beside the mark 



