THE TEACHING OF PSYCHOLOGY. 335 



One of the most delicate questions of the theory of muscular 

 sensations is that of defining tactual sensations. Having ab- 

 stracted from touch all that relates to the sense of effort, what is 

 left to constitute touch proper ? Sensations of temperature, and 

 what we call sensations of contact. But can there be sensations 

 of contact without there being more or less of pressure, traction, 

 etc. ? Is simple contact felt, otherwise than as heat or cold, when 

 we abstract all muscular sensation ? Might we not simply revert 

 from it, as did Biran, to the distinction between passive touch and 

 active touch, the latter including the effort ? But there appear to 

 be pathological cases where the touch persists while the muscular 

 sense is abolished, as, for example, where the patient with his 

 eyes closed can not tell where his limbs are, whether his arm 

 is raised up or lying down, etc.; but these cases relate to the 

 localization of sensations, another of the most complex ques- 

 tions, and to that of the perception of our body, which is no 

 less so. 



There is left the physiological question proper, that of the 

 seat of muscular sensation, on which there are two theories. Ac- 

 cording to what is called the centrifugal theory, the feeling of 

 muscular effort is connected with the outgoing current of the 

 motor influx. According to the other, the centripetal theory, it 

 is produced by the sensations returning from the member in 

 motion to the centers. Both of these theories find points of sup- 

 port in experiments made upon hysteric patients, who have in 

 these days become veritable analytical machines for the use of 

 psychology. On the one side are hysterics who, having lost the 

 muscular sense, and shut their eyes, have no knowledge of the 

 passive movements that are impressed on their limbs; and yet 

 this loss of muscular sense takes away none of the precision of the 

 motions which the subject executes; an observation which is 

 interpreted by some authors as favoring the centrifugal theory ; 

 because, centripetal sensations being abolished with these patients, 

 there must exist some condition of consciousness regulating their 

 movements, and that condition of consciousness can be determined 

 only by the outgoing current of the motor influx. There are, on 

 the contrary, other hysterics who, losing consciousness of the pas- 

 sive movements, lose also that of active motions, and become in- 

 capable of executing a single act with shut eyes, which is inter- 

 preted as meaning that voluntary motions are impossible when 

 centripetal sensations are abolished. This interpretation would 

 indicate that there exists no feeling allied with the motor discharge 

 and competent to regulate motions in the absence of centripetal 

 sensations. It is apparent that physiology has yet very far to go 

 before it can pretend to have solved these questions. But, as facts, 

 the experiments in question are very interesting ; and it happens 



