This chapter focuses on to a phase of animal psychology which has received, but inadequate treatment. This inadequacy is evident not only in the general psychologies, but also in special experimental investigations of animal intelligence. The vast importance of the human hand for perception becomes evident when we recognize how it answers to the eye, especially among the distance senses. The development of space perception follow in normal individuals upon the interaction of the eye and the hand, and this interaction works a continual meeting of the discriminations of the eye by those of the skin, mediated through the manipulating hand. In the case of the monkey the question arises whether the function of locomotion is so dominant in use of the so-called hands that that of “feeling” can be isolated out of the monkey’s contact experiences to build up perception.