TRANSACTIONS OF THE SECTIONS. 39 



D. Medicines that iudirectl}' retard oxidation. These may be divided into (1) those 

 that act upon the nerves, as prussic acid, morphia, and many other alkaloids ; 

 (2) those_ that act on the muscles, as rest, cold, salts of potass, lead salts, vera- 

 trine, digitaline, nicotine ; (3) those that alter the qualitative and quantitative 

 relationship of the blood to the vessels, as local and general bleediags^ starva- 

 tion, dilution, evacuation. 



The second great division of medicines consists of those vi^hich (E) directly or 

 (F) indirectly promote nutrition, or (G) directly and (II) indirectly retard it. 



The chemical actions which are concerned in the formation of the multitude of 

 organic substances of which the body is composed are far more complicated than 

 those comparatively simpler chemical actions on which oxidation depends. If 

 even now the different steps and processes, the helps and hindrances which affect 

 the formation of cai-bonic acid and water in the body are not yet determined, how 

 much less able must we be at present to comprehend the chemical actions which 

 take place in the formation of blood-globules, bones, muscles, nerves, &c. 



Many of those medicines that promote or retard oxidation at the same time 

 promote or retard nutrition. "^Tien they are present in excess, they render the 

 formation of different substances more rapid ; and when absent, the chemical actions 

 necessary for the formation of these substances are retarded or altogether stopped. 



E. Medicines that directly promote nutrition. Iron helps to form blood-globules ; 

 phosphate and carbonate of lime help to form bone ; cod-liver oil and other fatty 

 matters help to form adipose tissue. Gelatine perhaps helps to form cellular 

 tissue ; and phosphorus, still more doubtfully^ promotes the formation of nervous 

 tissue. 



F. Medicines that indirectly promote nutrition (1) by increasing the action of the 

 heart, (2) by lessening the resistance in the capillaries.— Alcohol, ether, chloro- 

 form, nitrous oxide, chloride of methyl, oleliant gas increase the action of the 

 heart by acting on the nerves. Ammonia almost immediately deprives motor 

 nei-ves of their power of exciting motion, while it intensely irritates the mus- 

 cidar structm-es. Of medicines that cause the capillaries to dilate curare is the 

 most remarkable. 



G. Medicines that directly retard nutrition, either (1) by themselves entering into 

 conibination with the organic substances of which the textures are composed, by 

 which combination the chemical changes that would othei-wise occur are stoppedf, 

 or (2) by the accumulation in the textures of any of the substances resulting 

 from the chemical changes in the textures. 



Lead, zinc, silver, copper, arsenic, antimony, and in some rare cases mercury, act 

 in small doses in the first way. Among the substances which act in the second 

 way must be included all the different products from each texture in their down- 

 ward com-se to carbonate of ammonia, water, and salts. Among these substances 

 carbonic acid and carbonic oxide ; organic acids from oxalic acid upwards; sugar; 

 fat ; nitrogenous substances from CiU'bouate of ammonia, urea, kreatine, indigo ; 

 animal qumoidine, to the first products formed from the albuminous substances! 

 H. Medicines that indirectly retard nutrition by lessening the action of the heart 



and increasing the resistance in the capillaries, by which actions the flow of 



blood through the textures is lessened. 



Four different actions may be distinguished, by any of which nuti-ition may be 

 lessened :— 1. By an action on the nerves of the heart, as by strychnia, nicotine, 

 conicme, digitahne ; 2. by an action on the muscular structure of the heart, as by 

 veratrme, colchicine, salts of potass; 3. by contraction of the capillaries in conse- 

 quence of an action upon the sympathetic''nene, as by morphine ; 4. by the reduc- 

 tion, quantitatively or qualitatively, of the state of the blood, as % bleeding- 

 starvation, excessive dilution, lead salts, mineral and organic acids. 



The actions of oxidation and nutrition are mutually dependent everywhere, and 

 no separation of these two actions in any part of the body actually talces place, 

 although, for clearness, I have considered them separately. The progress of all 

 accurate knowledge of the actions of medicines depends on exact chemical and 

 physical experiments ; and by the perfection of these alone vnll the practice of 



