408 VEGETABLE DRUGS 



follows constriction of the superficial blood vessels, which 

 is said to be due to tonic contraction of the smooth muscular 

 fibres of the vessel walls. The secondary vascular relaxa- 

 tion, and tendency to congestion in parts subjected to 

 cocaine anaesthesia, lessens the resistance of the tissues 

 (especially of sensitive structures, as the eye) to the irri- 

 tation of antiseptics and bacterial products. Therefore, 

 surgical operations performed under cocaine anaesthesia are 

 somewhat more prone to be followed by inflammation. 



Action Internal. — Digestive Tract. — Cocaine exerts a local 

 anaesthetic action upon the gastric mucous membrane, and 

 in this way lessens the appetite and sometimes stops vomit-, 

 ing. Intestinal peristalsis is increased by moderate doses, 

 but is decreased and destroyed by the paralytic action of 

 large doses of cocaine. 



Nervous System. — Ordinary medicinal doses produce no 

 marked effect upon the nervous system, except some mental 

 exhilaration. Full doses of cocaine stimulate the psychical 

 functions of the brain and cause intoxication, which is fol- 

 lowed, in poisoning, by stupor and convulsions. The con- 

 vulsions are mainly of cerebral origin, but may be due in 

 part to irritation of the spinal reflex centres. These latter 

 centres are first stimulated by toxic doses, but depression 

 and paralysis of the spinal cord follows ; the sensory before 

 the motor tract. " The sensory nerves are paralyzed and the 

 motor nerves depressed by toxic doses. The voluntary 

 muscles are stimulated by medicinal doses of cocaine, and 

 the alkaloid relieves fatigue and, experimentally, more than 

 doubles the response to stimuli in wornout muscles. Volun- 

 tary muscles are paralyzed by the local application of large 

 quantities of cocaine. 



Circulation. — The action of cocaine upon the heart and 

 vessels is not very marked, except in poisoning. The alkal- 

 oid is, however, a slight cardiac stimulant in moderate doses, 

 increasing the pulse-rate and tension. The action upon the 

 heart is caused by depression of the cardio - inhibitory 

 centres, and sometimes as well by depression of the cardiac 



