ANTHELMINTICS are remedies used either to kill or to cause the expulsion of intestinal worms, in the former case being known as vermicides, in the latter as vermifuges. Cathartics, since they cause the expulsion of worms, are vermifuges. Used alone, however, they are rarely wholly effective, it being neces sary to weaken, narcotize or kill the parasite first. For this pur pose the vermicides are used. The chief characteristic of the lat ter drugs is that they have a more profound effect on the parasite than on the host, since they are absorbed only very slowly by the intestinal canal. The vermicides produce their best results when taken on a fasting stomach, preceded by purgation and a very light diet and followed by thorough purgation within a few hours to remove the dead or weakened worms. Drugs frequently used in the treatment of hookworm are chenopodium oil, thymol and carbon tetrachloride ; in the treatment of tapeworm, aspidium and pelletierine ; in the treatment of roundworm, santonin and spigelia.