CHAPTEE II 



SENSI1UL1TY OF THE INTERNAL OKCANS 



CONII:NTS. 1. Classification of internal sensations. 2. Common sensation of 

 the body or coenaesthesia. ':>. Pain in tlie internal organs and tissues. 4. Ali- 

 nn'iitarv needs (hunger and thirst). 5. Sexual desire. 6. The muscular sense : 

 s, nubility of muscles, tendons, and joints. 7. Innervation sense in the centres of 

 voluntary movement. 8. Active tactile perceptions and their components. 9. The 

 siil'i-miM'ious sense of muscular tone and its variations in reference to the functions 

 of the labyrinth. Bibliography. 



ALL internal organs and tissues provided with afferent nerves have 

 a greater or less degree of sensibility. The sensations aroused from 

 the peripheral terminations of these nerves are almost always 

 independent of external stimuli, and depend as a rule upon the 

 somatic conditions inherent in the organism. They are accord- 

 ingly grouped together under the name of Internal or Bodily 

 Sensations. 



While the specific sensations aroused by the action of the 

 outer world are the basis from which our intellect is developed 

 and perfected, the internal sensations do not normally give any 

 clear indications of our internal world. Nevertheless they are of 

 great importance from the psychological and philosophical point 

 of view, as was well brought out by Cabanis at the beginning of 

 the last century in his famous book Rapports du physique et du 

 moral de I'homme. He showed that, even when they do not pass 

 the threshold of consciousness, the internal sensations may send 

 impressions to the brain which alter our psychical personality. 

 On the other hand we know that they exercise reflexly, along 

 ill-- efferent nerves, a controlling inlluence upon all the functions 

 of the vegetative and animal life. 



I. The physiological study of the internal sensations of the 

 nrvraiis has progressed very little because their indetinite char- 

 acter usually makes a strict application of experimental methods 

 impossible. Physiologists have been content to hand over the 

 study of this category of phenomena, to clinicians, who have 

 frequent opportunities of investi-nlim;- them in their patients, in 

 whom they are often exaggerated and become more conspicuous, 



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