45 8 MATERIA MEDIC A AND THERAPEUTICS. 



which regulate the vessels. But for practical purposes it is 

 highly important to keep the action of drugs upon the protoplasm 

 of an organ quite distinct from their action upon the organ 

 through its nerves or its blood supply. 



Alteratives. The subject of metabolism introduces us to a 

 term applied to certain drugs, namely, alteratives. This word, 

 like many other terms in therapeutics, never had an exact 

 application, and therefore defies correct definition. Still, it is 

 retained as a useful word, and its meaning may be discussed if 

 it cannot be defined. We have seen that we can increase the 

 amount of work done by an organ in several ways, through 

 food, air, local stimulation, etc., which make it build up and 

 break down more actively both its pabulum, the lymph, and its 

 own proper elements : which, in one word, exercise it. Certain 

 medicinal substances also are found to increase metabolism, the 

 chief of which are Mercury and Iodine, Phosphorus, Antimony, 

 and Arsenic, Sulphur or Sulphides, and certain doubtful vege- 

 table agents, such as Sarsa and Guaiacum. The particular 

 way in which each of these drugs increases tissue waste is 

 given under its own head, as far as it is known. It naturally 

 occurs to us, that the action of these medicines is another form 

 of exercise of the tissues. When Mercury and Iodine, for 

 example, have entered into combination with living protoplasm, 

 and been again disengaged or thrown out of combination with 

 it in the metabolic products, they have made it do a certain 

 amount of work : and to a corresponding extent they have 

 effected a change and a renewal of its proper molecules ; they 

 have hastened its nutrition ; their action may be said to be 

 alterative. We find that an essential condition of the success of 

 alterative drugs is a free supply of the normal sources of meta- 

 bolism, food and air, just as it is of physical exercise, that the 

 constructive part may keep pace with the destructive part of 

 metabolism. If food and air fail, the health rapidly breaks 

 down, the body wastes, and death may result. Possessing a 

 powerful and peculiar action like this, these medicinal agents 

 fully deserve the name of alteratives, and any method of treat- 

 ment which may be founded upon their action is incomplete 

 unless it include abundant feeding and fresh air. 



Opposed to the alteratives are an important class of drugs 

 which diminish metabolism. Alcohol has this action, appa- 

 rently by being itself so readily oxydised in the tissues that it 

 robs the cells, as it were, of oxygen, while it also binds the 

 oxygen more firmly to the red corpuscles, and thus in two 

 different ways spares tissue change. Quinia also lowers oxy- 

 genation, and has a further influence in preventing oxydation 

 of protoplasm, which is imperfectly understood. Probably 



