This book records the results obtained from the study of the twins Johnny and Jimmy, which received considerable notoriety in the newspaper during the past year. The purpose of the investigation was to study the process of development as it is manifested in the growth of particular behavior patterns of the human infant and to evaluate the influence of exercise or use of an activity on its development.
Study was begun on the twins at birth. Johnny was taught various ontogenetic behavior activities, such as swimming, diving, ascending inclines, skating, manipulation of graded stools, manipulation of graded boxes and tricycling. These activities are illustrated by plates and are astounding as showing what can be accomplished by such a young infant.
At the end of the period of study the mental rating of the twins was 94 for Johnny and 91 for Jimmy. The author states: "Although Johnny had enjoyed earlier