MATERIA MEDICA 



Medicines are substances which have the power of so modifying 

 the actual state of the organs, as to render them applicable to the 

 cure of disease. They differ from remedies^ which are of a more 

 generic nature; and include all the various means employed to alle- 

 viate or cure disease : thus heat, cold, electricity, a surgical opera- 

 tion, &c., are all remedies, but cannot be called medicines. 



Materia Medica is the science which treats of medicinal sub- 

 stances ; Therapeutics — the application of remedies to the treat- 

 ment of disease. Pharmacy is the art of compounding or preparing 

 medicines for use. 



A complete knowledge of medicines includes an acquaintance with 

 their jjJiysical characters^ such as of colour, taste, odour, general 

 appearance; iheu chemical properties ; X\\e,\Y natural (iwdi botaiiical 

 history; their modes of groicth^ collection^ iireservation^ &c. ; their 

 therapeutical applications; their physiological properties^ or their 

 method of affecting the healthy system ; and their toxicological pro- 

 perties^ or their poisonous effects. It is hence obvious that a correct 

 knowledge of Materia Medica presupposes some acquaintance with 

 Natural History, Botany, and Chemistry ; and that of Therapeutics 

 requires some familiarity with Anatomy and Physiology, and also 

 with the principles of Mental and Moral Philosophy, as well as of 

 the general powers or forces of nature, such as light, heat, electri- 

 city, and magnetism. 



Along with medicines proper, it is usual to consider a set of sub- 

 stances called aliments^ which are often very useful as therapeutic 

 agents, though they cannot be considered as medicinal in their 

 action. They possess nutritive qualities, and when swallowed, they 

 are digested and converted into chyle. Medicines, on the contrary, 

 produce their effects upon the system, not by undergoing change 

 through the digestive process, but either by being absorbed into the 

 circulation, and thus influencing the blood and the various secretions 

 by virtue of some chemical influence, or by means of nervous com- 

 munication between distant parts and the part to which the remedy 

 is immediately applied. 



Some few medicines appear to act upon the system mechanically^ 

 as some of the anthelmintics which expel worms from the bowels, 

 simply by the mechanical irritation they produce ; bran is thought 



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