42 G. V. HAMILTON 



Monkey 3. Age, 5 years (estimated). Macacus rhesus. About 

 3 years in captivity. A truculent, untamable animal, but a 

 fairly good subject. 



Monkey 2. Age, 1.5 years (estimated). Macacus 



(species undetermined). About i year in captivity. Timid, 

 but exceptionally resourceful in meeting outdoor situations 

 when he was given the freedom of the ranch. His timidity 

 doubtless affected his behavior. 



Monkey i. Age, 1.5 years (estimated). Macacus rhesus. 

 About I year in captivity. A comparatively stupid animal, 

 but uniform in behavior during the experiment. 



Dogs 



The sixteen dogs of the following list range in age from thirty- 

 six days to three years. With the exception of the two adults 

 (Dogs I and 2), they are all descended from a common sire, the 

 subject of my previously published "An Experimental Study 

 of an Unusual Type of Reaction in a Dog." (3) This sire was a 

 Boston Terrier of impure breed. The six puppies that are 

 designated " F2 " in the list below were from a mongrel bitch 

 of the small hound type. Their mother was unavailable for 

 experiment. The eight puppies of the " Fi " group were from 

 an English Setter bitch, — " Dog i " of the list. 



Dog. I. Age, 3 years. English Setter. Mother of dogs 3, 

 7, 8, 9, II, 12, 14 and 18 (one litter). She was untrained, hence 

 a study of her behavior under natural conditions was easily 

 possible. It was found that whenever she sighted or scented 

 her prey she would inhibit every visible movement of her body 

 but a slight tremor and a wagging of her tail, and would stand 

 thus, in a rigid attitude, for several minutes before making a 

 final dash to seize the object of her attention. A tendency 

 to inhibit, momentarily, all active movements when prey is 

 first discovered is not limited to any special breed of dogs: it 

 is the prolongation of this momentary inhibition that so marks 

 the behavior of the English Setter. This reactive tendency 

 of the mother of my puppies is of much interest for the present 

 investigation. 



Dog 2. Age, I year (estimated). Great Dane -mongrel. His 

 tendency to look to his master for cues to action marked him as 

 characteristicallv different from all the other dogs of my experi- 



