40 G. V. HAMILTON 



The many gaps in the age and phyletic series are due to the 

 fact that the results obtained from many of my subjects had 

 to be rejected for various reasons. Some of the subjects were 

 stolen and some died before their trials were completed; in 

 some cases I could not be reasonably sure that a possible diffi- 

 culty in discriminating one exit door from another did not exist ; 

 and many unavoidable interruptions rendered it impossible to 

 make use of all the subjects that were available for experiment. 

 It is much to be regretted that the list given below includes 

 no human subjects between the ages of twenty-six months and 

 eight years; the writer's wholly undeserved local reputation as 

 a vivisectionist seemed to create a stubborn unwillingness on 

 the part of parents to supply young children for experimental 

 work. 



Human Subjects 



Man I. Age, 34 years. Native (Spanish-Indian) Californian. 

 Ranch laborer in the experimenter's employ. A man of limited 

 education, but of average intelligence for his class. He went 

 through his trials in the stolid, unemotional manner that char- 

 acterised his work in the fields. The " boss " wanted him to 

 walk into and out of an enclosure 100 times, and he did so with- 

 out asking questions or shirking his task. 



Boy 7. Age, 15 years. American, of original English descent. 

 Grocer's boy. Countr}^ school education. He was shy and 

 nervous at the beginning of the experiment, and always seemed 

 to be more or less affected by a fear of appearing stupid. 



Boy 6F1. Age, 13 years. Father Italian, mother Swedish. 

 Country schoolboy. He was less alert, mentally, than were 

 his brothers, who are described below. 



Boy 5F1. Age, 11 years. Brother of Boy 6F1. Cotintry 

 schoolboy. Volatile, alert, and rather distractible. 



Boy 4F1. Age, 10 years. Brother of Boys 6F1 and 5F1. 

 Country schoolboy. Relatively precocious, and an excellent 

 subject. 



Boy 3. Age, 10 years. Native (Spanish-Indian) Californian. 

 Country schoolboy. Bright, but rather shy, and too nervously 

 eager to please the experimenter. 



Girl I. Age, 10 years. American of Scotch descent. Until 

 recently a student in the public schools of Cambridge, Mass. 

 Her superiority of school training, and her very considerable 



