Aspidium Felix-Mas, Male Fern. The preparations of this drug are often uncertain, and, as it contains a toxic principle profoundly influencing the nervous system, great care should be taken to have a good preparation possessing to the full the somewhat unstable substance acting as a gastro-intestinal irritant. Saline or vegetable laxatives should follow its administration. Do not give oil, since it facilitates absorption of the toxic agent. Merck's oleoresin of male fern may be given in doses of I f5 every half hour until 3 doses are taken. The oleoresin should be well shaken and administered in capsules. It is commonly followed by a dose of calomel and jalap, but this may not always be necessary.