THE PRODUCTION OF MOVEMENT. 379 



rlioea of fear, the biliary disturbances wliicli sometimes 

 tollow upon rage, etc. The watering of the moiith at the 

 sight of succulent food is well known. It is difficult to 

 follow the smaller degrees of all these reflex changes, but 

 it can hardly be doubted that they exist in some degree, 

 even where they cease to be traceable, and that all our 

 sensations have some visceral effects. The sneezing pro- 

 duced by sunshine, the roughening of the skin (gooseflesh) 

 which certain strokings, contacts, and sounds, musical or 

 non-musical, provoke, are facts of the same order as the 

 shuddering and standing up of the hair in fear, only of less 

 degree. 



Effects on Voluntary Muscles. Every sensorial stimulus 

 not only sends a special discharge into certain particular 

 muscles dependent on the special nature of the stimulus in 

 question — some of these special discharges we have studied 

 in Chapter XI, others we shall examine under the heads 

 of Instinct and Emotion — but it innervates the muscles 

 generally. M. Fere has given very curious experimental 

 proofs of this. The strength of contraction of the subject's 

 hand was measured by a self-registering dynamometer. 

 Ordinarily the maximum strength, under simple experimen- 

 tal conditions, remains the same from day to day. But if 

 simultaneously with the contraction the subject received a 

 sensorial impression, the contraction was sometimes weak- 

 ened, but more often increased. This reinforcing effect has 

 received the name of dynamogeny. The dynamogenic value of 

 simple musical notes seems to be proportional to their loud- 

 ness and height. Where the notes are compounded into sad 

 strains, the muscular strength diminishes. If the strains are 

 gay, it is increased. — The dynamogenic value of colored lights 

 varies with the color. In a subject * whose normal strength 

 was expressed by 23, it became 24 when a blue light was 



*The figures given are from an hysterical subject, and the differences 

 are greater than normal. M. Fere considers that the unstable nervous 

 system of the hysteric (' ces grenouilles de la psychologic ') shows the law 

 on a quantitatively exaggerated scale, without altering the qualitative rela- 

 tions. The effects remind us a little of the influence of sensations upon 

 minimal sensations of other orders discovered by Urbantschitsch, and re- 

 ported on page 29 of this volume. 



