106 YETERIXART MATERIA MEDICA. 



modic, and anodyne. It is a stimulant to the heart, 

 respiration, and spinal cord if given in small doses, 

 while large doses paralyze the secretory and motor 

 nerve endings, but stimulate the sympathetic system. 

 Its internal administration produces a dryness of the 

 mucous membranes of the nose, mouth, throat, and 

 larynx; while the gastric and intestinal secretions, 

 although at first decreased, are soon reproduced in in- 

 creased quantity. The heart rate at first is slowed, 

 but shortly becomes very rapid and vigorous, the 

 pulse being doubled in rapidity, arterial tension is 

 raised, and circulation increased. This is brought 

 about by belladonna directly stimulating the cardiac 

 sympathetic and paralyzing the intracardiac inhibi- 

 tory ganglia, which, while stimulating the accelera- 

 tor apparatus, decreases the inhibitory power. Like 

 other members of the same group, belladonna stimu- 

 lates the vasomotor ganglia over the entire body, 

 with paralysis by over-stimulation; thus the heart 

 weakens, vessels become relaxed, blood pressure is 

 greatly lowered, and if the action of the drug is al- 

 lowed to continue, complete motor paralysis ensues, 

 with delirium, stupor, and finally death by asphyxia 

 (paralysis of respiration) . Belladonna lessens intra- 

 ocular pressure, and by its systemic as well as local 

 administration dilates the pupil of the eye. The dil- 

 atation reaches its maximum in the dog in from 

 twenty to twenty-five minutes, in herbivora in from 

 one-half to three-fourths of an hour, and its effects 

 may continue in a lesser degree for several days. 

 The brain is congested by belladonna and more or 



