358 VEGETABLE DRUGS 



belladonna, but is considerably lessened, or suppressed, in 

 poisoning by the drug. Experiments upon man show that 

 the urinary solids are increased: urea and uric acid to a 

 slight extent ; sulphates and phosphates to a considerable 

 degree. 



Muscles and their Nerves. — The involuntary muscles are 

 not affected by moderate doses of belhidonna. Their motor 

 nerve terminations are depressed by full medicinal doses, 

 and the muscles themselves are depressed and paralyzed by 

 poisonous doses. The motor nerve endings, in voluntary 

 muscles, are partly paralyzed by toxic doses of belladonna. 

 In accordance with the foregoing, intestinal peristalsis is 

 increased by moderate doses of the drug, by depression 

 of the inhibitory nerve terminations in the smooth muscle 

 of the intestinal walls; bnt is diminished by the action 

 of large doses, by paralyzing the involuntary muscle. 

 Again: the pneumogastric terminations are depressed in 

 the heart by moderate doses, while the heart muscle is 

 paralyzed by large quantities of belladonna. 



A like depressing influence is believed to be exerted 

 upon the efferent nerve endings of the ud striped muscles of 

 the bladder, urethra, uterus and vagina, as well as upon the 

 muscles of these organs. Belladonna acts medicinally as 

 an antispasmodic in relation to the muscles. 



Respiration. — Small doses of atropine do not affect the 

 respiration. Large therapeutic doses make the respiratory 

 movements quicker and deeper, by stimulation of the 

 medullary and spinal respiratory centres. Fatal doses 

 produce respiratory failure and asphyxia, owing to paralysis 

 of the respiratory centre and the peripheral vagus filaments 

 concerned with the respiratory movements. Belladonna 

 also paralyzes the peripheral fibres of the pneumogastric 

 nerve in the bronchial tubes and acts therapeutically as 

 follows: 1. As a respiratory stimulant; the drug is gene- 

 rally inferior to strychnine in this respect, but acts effi- 

 ciently in certain conditions, as in poisoning by opium, 

 aconite, physostigma, etc. 2. As an antispasmodic, by 



