Page:American Journal of Psychology Volume 21.djvu/559

Rh It will be recalled that Sherrington found that in the spinal frog "the initial posture of the limb distinctly affects the character of the reflex movement even in the absence of cutaneous organs." This fact, together with Munk's results and criticism of Mott and Sherrington, takes us again to Judd's position that in the animal relatively low in the phyletic scale the kinaesthetic areas play a more important function than they do in the higher animals for the reason that in the latter the special senses have become more highly differentiated and have accordingly, to a degree at least, usurped the original primacy of kinsesthetic centres and therefore play a more important part in volitional activity. However hypothetical Judd's position may appear, it certainly possesses the advantage of facilitating interpretation, an advantage which warrants its application. If we assume that the original undifferentiated form of sensation is of the tactual-kinaesthetic type and that from this original type all other forms of sensation have been gradually differentiated, it is clear that in animals low down in the scale of evolution the original type of sensation must necessarily perform the important function of the sensory cue for voluntary movement. On the other hand, in animals high in the same scale the other sense processes are so highly specialized and developed that, when measured in terms of relative discrimination, they far surpass the original type from which they took rise, and may now play the principal r61e in voluntary action. Moreover if in making a new and conscious adaptation which involves discrimination and choice and therefore voluntary movement the important thing is the correct grasp of the situation rather than the consciousness of the movement as such, then it also follows that the sense organs of later development naturally play a primary r61e for the reason that their discrimination is finer, and for the additional reason that they act at a distance.

(3) Pathological Cases. Disease has done, not infrequently, what is impossible to experimentation upon human beings; it has destroyed the sense processes, and given us the general relation of these processes to voluntary movement in very much the same way as the physiological experiments of Mott and Sherrington and Munk reveal them in the case of the monkey. It is therefore in place to review here a number of typical cases of anaesthesia and to attempt an interpretation of their bearing upon voluntary movement. One naturally begins with Strumpell's celebrated case. Of the extent of this boy's anaesthesia James says that he "was totally anaesthetic without and within