m MEDICAL SCIENCE. 67 



In this way those articles of the Materia Medica 

 which had nothing but loathsomeness to recommend 

 them have been gradually dropped, and are not like 

 to obtain any general favor again with civilized com- 

 munities. The next culprits to be tried are the poi- 

 sons. I have never been in the least sceptical as to 

 the utility of some of them, when properly employed. 

 Though I believe that at present, taking the world at 

 large, and leaving out a few powerful agents of such 

 immense value that they rank next to food in impor- 

 tance, the poisons prescribed for disease do more hurt 

 than good, I have no doubt, and never professed to have 

 any, that they do much good in prudent and instructed 

 hands. But I am very willing to confess a great jeal- 

 ousy of many agents, and I could almost wish to see 

 the Materia Medica so classed as to call suspicion upon 

 certain ones among them. 



Thus the alien elements, those which do not properly 

 enter into the composition of any living tissue, are the 

 most to be suspected, — mercury, lead, antimony, silver, 

 and the rest, for the reasons I have before mentioned. 

 Even iodine, which, as it is found in certain plants, 

 seems less remote from the animal tissues, gives une- 

 quivocal proofs from time to time that it is hostile to 

 some portions of the glandular system. 



There is, of course, less prima facie objection to 

 those agents which consist of assimilable elements, 

 such as are found making a part of healthy tissues. 

 These are divisible into three classes, — foods, poisons, 



