46 G. V. HAMILTON 



Discussion of Table i . In the light of ■ analyses that are to 

 follow, this table has a largely negative value. It shows how 

 misleading a single objective measure of ability to profit by 

 experience may be. For example, the three-year old mother 

 of the Fi puppies (Dog i) made 324 separate efforts to open 

 exit doors during 100 trials, whilst her fifty-three-days old 

 puppy (Dog 12F1) has a record of only 307 efforts to open 

 doors. Her record is also greater than that of three of the other 

 puppies (Dogs 3F1, 5F2, and 13F2). Table i also shows that 

 immature Monkey 2 has a lower record than either of the two 

 adult monkeys; and that the record of mature Cat 2 exceeds 

 that of iifty-six-days old Cat 5 by ten efforts to open doors. In 

 the case of the monkeys, the apparent inconsistency of onto- 

 genetic findings becomes all the more striking when we take 

 into account the fact that at 1.5 years of age the Macacque is 

 scarcely half -grown, and sexually immature. 



When we enter upon a discussion of the different modes of 

 searching for unlocked doors, and attempt to isolate the specific 

 reactive tendencies to which these may be attributed, it will 

 be seen that a genetically superior reactive tendency may lead, 

 in some of its manifestations, to an actual increase in number 

 of efforts to open doors. For the present, however, it is desirable 

 to subject the data contained in table i to further analysis in 

 order to discover whether or not there is a general tendency for 

 increasing age and phyletic position to decrease the number 

 of efforts to open doors. To this end the various subjects will 

 be divided into age and phyletic groups, and the averages for 

 each of these groups will be compared. 



Since the results obtained from the normal human subjects 

 whose ages range from eight to thirty-four years do not present 

 individual variations from their general average which can be 

 clearly traced to age differences, these eight subjects will be 

 included in a single group. The two defective human subjects — 

 Man A and Boy A — cannot properly be classed together, hence 

 their individual results will appear separately in the table of 

 averages (table 2, below). The human infant (Boy i), the 

 monkey whose failing vision affected his behavior (Monkey 4), 

 and the horse should, for obvious reasons, appear separately 

 in a table of averages. The mature dogs and mature cats each 

 form an age group, as do also the kittens. In the case of the 



