CLASS III. 2. 1. S. OF VOLITION. 333 



3. 2. 2. which originate from excess of sensorial power, or from 

 efforts to relieve disagreeable sensation, and are afterwards con- 

 tinued by habit. 



3. Tremor senilis. Tremor of old age consists of a perpetual 

 trembling of the hands, or of the head, or of other muscles > 

 when they are exerted; and is erroneously called paralytic; and 

 seems owing to the small quantity of animal power residing in 

 the muscular fibres. These tremors only exist when the affected 

 muscles are excited into action, as in lifting a glass to the mouth, 

 or in writing, or in keeping the body upright; and cease again, 

 when no voluntary exertion is attempted, as in lying down* 

 Hence these tremors evidently originate from the too quick ex- 

 haustion of the lessened quantity of the spirit of animation. So 

 many people tremble from fear or anger, when too great a part 

 pf the sensorial power is exerted on the organs of sense, so as to 

 deprive the muscles, which support the body erect, of their due 

 quantity. 



4. Brachiorum paralysis. A numbness of the arms is a fre- 

 quent symptom in hydrops thoracis, as explained in Class I. 2. 

 3. 14. and in Sect. XXIX. 5. 2.; it also accompanies the asthma 

 dolorificum, Class III. 1. 1. 11. and is owing probably to the 

 same cause in both. In the colica saturnina a paralysis affects 

 the wrists, as appears on the patient extending his arm horizon- 

 tally with the palm downwards, and is often attended with a tu- 

 mour on the carpal or metacarpal bones. See Class IV. 2. 2. 10. 

 and I. 2. 4. 8. 



Mr. M , a miner and well-sinker, about three years ago, 



lost the power of contracting both his thumbs; the balls or mus- 

 cles of the thumbs are much emaciated, and remain paralytic. 

 He ascribes his disease to immersing his hands too long in cold 

 water in the execution of his business. He says his hands had 

 frequently been much benumbed before, so that he could not 

 without difficulty clench them; but that they recovered their mo- 

 tion, as soon as they began to glow, after he had dried and co- 

 vered them. 



In this case there existed two injurious circumstances of dif- 

 ferent kinds; one the violent and continued action of the muscles, 

 which destroys by exhausting the sensorial power; and the other, 

 the application of cold, which destroys by defect of stimulus. 

 The cold seems to have contributed to the paralysis by its long 

 application, as well as the continued exertion; but as during the 

 torpor occasioned by the exposure to cold, if the degree of it be 

 not so great as to extinguish life, the sensorial power becomes 

 accumulated; there is reason to believe, that the exposing a pa- 

 ralytic limb to the cold for a certain time, as by covering it with 



