DEPARTMENT OF GENETICS, 131 



until after 3 weeks of daily training were the dogs in this litter going through 

 the apparatus anywhere near the required 10 times per day. The litter as a 

 whole showed the same type of sensitiveness and fear as shown by the father. 

 There were variations: e. g., one was markedly less sensitive than the others, 

 making as many as 9 trials on the sixteenth day ; and one was markedly more 

 full of fear, after 40 days still refusing to go through the apparatus at all. 



In comparison with these results the behavior of another litter (five pups 

 of the same age), trained at the same time, from a different mother and the 

 same father as the first litter trained (ex Psych by Engadin), serves as an 

 excellent control. The dogs in this litter went through the apparatus at once, 

 with none of the demonstrations of fear shown by the offspring of Prince at 

 the movement of the doors or at the buzzers. In 6 days all but one of this 

 litter were making 10 trials a day. The one exception acquired a fear complex 

 after 2 days in connection with the side doors Sl and Sr. The dog would enter 

 the apparatus freely and was not bothered by the buzzers or the movement of 

 other doors, although the course of the trials was upset. This is quite dif- 

 ferent from the general fear shown by the offspring of Prince. The one 

 surviving pup in a litter ex Psych by Prince, although not yet introduced to 

 the association apparatus, shows strikingly certain peculiar characteristics of 

 general behavior shown by the other pups from Prince. 



It looks very strongly as though even in these very first experiments the 

 inheritance of a dominant disposition or temperament is seen. This suggests 

 the results of Davenport's study of periodic outbreaks of violent temper in 

 man, which was shown to be a dominant trait. Temperament and the action 

 of internally secreting glands are believed to be closely related, so that it is 

 possible that the heritable material at the basis of this behavior in the dogs 

 may be both glandular rather and nervous. 



While the reactions just discussed are controlled mainly by temperament, 

 the formation of the associations as measured by the proportion of correct 

 turns is more of an index of intelhgence. So far no very marked differences 

 have appeared in this regard between the dogs trained ; but as these have all 

 been dachshunds, this does not preclude the appearance of marked differences 

 when another breed is studied. 



The behavior of dogs in the presence of other animals forms a rich field for 

 the identification of characteristics of behavior. Individual differences between 

 dogs in the same situation appear with clearness, but the evaluation of these 

 differences, however obvious they may be, is a matter of considerable diffi- 

 culty, and so far has not been successfully accomplished. Notes upon 

 barking offer possibilities, since barking consists of a series of unit explosions 

 that may be counted. Certain animals, when presented safely caged to the 

 dogs, call forth constant barking, others no sound at all. Some dogs will 

 always bark at certain animals, while others never bark at the same animals. 

 Most characteristic of certain dogs are the intensities of the interest reactions, 

 and these can be classified only in the most unsatisfactory and rough manner. 

 There has been no difficulty in recognizing the extremes, even in the one 

 breed; the same characteristics remain at different ages and appear under 

 different circumstances. The dog that paid no attention to a mouse when a 

 young pup, at a year shows no interest in mice, rats, or guinea-pigs; he fears 

 the association apparatus. The bitch that most violently killed mice when a 

 young pup, at a year fights furiously to catch any caged animal and has not the 

 slightest fear of the association apparatus. All except one pup in the litter ex 

 Cocoa by Prince showed fear at the presence of a guinea-pig in the kennel, 

 and this was the one that soonest lost his fear of the association apparatus. 



