ACTION OF BELLADONNA AND ATROPINE 357 



panied by more convulsive movements. Various explana- 

 tions have been offered to reconcile these phenomena. The 

 prevalent theory is that, following complete paralysis of the 

 spinal cord, the motor and sensory tracts recover before the 

 inhibitory centres, so that normal stimuli pass through the 

 latter unrestrained and result in convulsions. 



Nerves— The action of belladonna upon the nerve end- 

 ings is extremely important, and represents, to a consider- 

 able degree, the therapeutic value of the drug. The 

 peripheral motor nerve terminations, and, to a less extent, 

 their trunks, are depressed and paralyzed. This is never 

 so complete, however, but that there is some voluntary 

 power left in an animal fatally poisoned. Depression and 

 loss of function of the afferent nerves come on more slowly, 

 and exist to a less degree. Belladonna, then, when applied 

 locally or given internally, is an anodyne, but is far inferior 

 in this respect to opium; and, whereas opium acts centrally, 

 belladonna acts peripherally. The terminations of all secre- 

 tory nerves are also depressed and paralyzed by belladonna, 

 and secretions are therefore diminished. 



Secretions. — Dryness of the mouth is one of the first 

 physiological symptoms following the administration of 

 belladonna. This is due to paralysis of the peripheral 

 terminations of the secretory nerve (chorda tympani) of the 

 submaxillary gland, and of the secretory nerve endings of 

 the other salivary and mucous glands in connection with 

 the mouth. Another characteristic effect of belladonna 

 consists in the production of dryness of the skin, which 

 follows the action of the drug in paralyzing the peripheral 

 nervous filaments supplying the secretory cells of the 

 sudoriparous glands. In the same manner the tracheal 

 and bronchial secretions are diminished, and also the 

 secretion of milk (anti-galactagogue action), by depression 

 of the terminations of the secretory nerves. The drug does 

 not exert any decided influence upon the secretions of the 

 digestive tract, as before stated. The amount of urine is 

 sometimes increased after the ingestion of small doses of 



