ACTIONS OF MEDICINES 23 



while another yields curare, which paralyses the peripheral 

 endings of motor nerves. But even the same drug some- 

 times yields antagonistic active principles. From opium 

 are obtained the soothing anodyne morphine, the convulsant 

 thebaine, and the emetic apomorphine. Calabar bean 

 yields eserine which depresses, and calabarine which stimu- 

 lates the spinal cord. Jaborandi yields pilocarpine and its 

 antagonist jaborine, the former stimulating, and the latter 

 paralysing the ends of secretory nerves. 



The grouping of medicines according to their actions has 

 not hitherto been of much more practical value than their 

 chemical or botanical classification. The precise actions of 

 many medicines are only now becoming definitely known. 

 Many, moreover, have a variety of actions, and hence have 

 to be included in several groups. Alcohol, for example, is 

 stimulant, irritant, narcotic, and sedative, as well as nutrient, 

 antiseptic, and antipyretic. Opium is narcotic, anodyne, 

 and hypnotic ; but it also stimulates certain patients, and 

 tetanises others. 



Disregarding the classifications hitherto adopted, students 

 and practitioners will find it advantageous to study the 

 actions of medicines upon the chief organs and functions of 

 the body : 



Actions of Medicinal Agents. 



I. Local and general actions : absorption and distribu- 

 tion. 

 II. Elective affinity between drugs and particular tissues 



or cells : elimination. 



III. Effects on different classes of patients. 

 IV. Modifying influences of Climate and Temperature, 

 Habit, Idiosyncrasy, Disease, and Surroundings, 

 etc. 



Curative Systems : Allopathy, Homoeopathy. 



On Protoplasm, Blood, and Bacteria. 



Antiseptics : Disinfectants : Germicides : Deodorisers : 

 Antiperiodics. 



