PREFACE. 



to collect them. Orfila says, " We were one day in the 

 shop of an apothecary who had several times furnished us 

 with extract of hemlock, which we had administered to dogs, 

 to the dose of 10 drachms without producing any serious 

 accident. We endeavoured to prove to him that the 

 medicine was badly prepared, and in order to convince 

 him effectually, we swallowed, in the presence of several 

 persons who happened to be in his shop, a drachm of this 

 extract (72 grains) dissolved in two drachms of water. 

 We felt no ill effect from it, whilst 20 to 30 grains of the 

 extract, well prepared, would probably have proved fatal 

 to us." This observation upon the badness of shop pre- 

 parations of this drug is confirmed by Mr. Pereira ; and 

 Dr. Christison considers it absolutely necessary to begin 

 the inquiry into its effects anew, the preparations hitherto 

 employed being of very little energy, or absolutely inert. 

 Dr. Hancock makes the same remark upon shop Sarsa- 

 parilla. 



If it should appear that many exotic plants have been 

 admitted, the importance of which is possibly not 

 greater than that of many European plants which have 

 been rejected, it should also be considered, that the 

 latter have been expelled from practice upon definite 

 grounds, and that no such careful investigation of the 

 former has yet been made ; moreover, the very nature 

 of the climate of tropical countries generally causes the 

 properties of plants to be more concentrated and com- 

 pletely elaborated than in northern latitudes. It may 

 possibly be said that numerous species have been admitted, 

 the properties of which are dietetic or poisonous rather 

 than medicinal. In noticing alimentary plants the author 

 has followed the example of the College of Physicians who 

 admit Barley, Wheat, Oats, Arrow-root, Sago, &c. into the 

 Pharmacopoeia ; and he has endeavoured to select such 

 alimentary plants only as furnish the diet of a sick person. 

 With respect to poisons it is to be remembered that the 

 energy which renders them dangerous if taken in excess, 

 may also cause them to be, in the hands of skilful prac- 



