CELL-CONTENTS AND FORMS OF CELLS. 165 



crystalline double compounds may be formed. Picric acid forms 

 characteristic crystals with a number of the alkaloids. Wormley's 

 Reagent, or a solution of bromine in hydrochloric acid, gives 

 definite microscopic crystals with some of the alkaloids, as atro- 

 pine, hyoscyamine, and veratrine. Auric chloride and platinic 

 chloride both form characteristic double salts with a number of 

 the alkaloids. There are a number of other reagents which are 

 used in the study of the localization of alkaloids in plants. Most 

 of these depend upon certain color reactions. While it is true 

 that the alkaloids give rather striking colors with certain reagents, 

 yet, as a rule, they are of little value except when the alkaloids 

 are in a pure condition. This same objection holds, but with some- 

 what less force, to the employment of the alkaloidal reagents 

 just mentioned. 



FAMILIES YIELDING ALKALOIDS. It is very difficult to deter- 

 mine from the literature of the analyses as to how widely distrib- 

 uted alkaloids are in plants. Time and again principles, which 

 give definite reactions with certain alkaloidal reagents, are subse- 

 quently shown to be other than alkaloids. In enumerating the 

 families in which alkaloids occur we do not mean to say that 

 they are lacking in the families not mentioned here. Alkaloids 

 are seldom found in the Cryptogams, being confined, with few 

 exceptions, to the poisonous fungi, as Amanita of the Agaricacse. 

 Among the Monocotyledons they are found in the Palmse and the 

 Liliaceae. They are more widely distributed in the Dicoty- 

 ledons, occurring in the following families : Piperacese, Chenopo- 

 diacese, Ranunculaceae, Berberidaceae, Menispermaceae, Lauraceae, 

 Papaveraceae, Leguminosse, Erythroxylaceae, Rutaceae, Aquifolia- 

 cese, Sapindacese, Sterculiaceae, Punicaceae, Umbelli ferae, Logania- 

 ceae, Apocynaceae, Solanaceae, Rubiaceae, and Lobeliaceae. 



THE AMOUNT OF ALKALOIDS in plants varies under different 

 climatic conditions and is also very much influenced by culti- 

 vation (see chapter on "Cultivation of Medicinal Plants"). 

 For these reasons there is a wide range in the alkaloidal content of 

 drug products, and, as the alkaloids are among the most poisonous 

 constituents known, the various pharmacopoeias have set alkaloidal 

 standards. At the International Conference for the Unification of 

 Pharmacopceial Formulae for Potent Medicaments held in Brus- 



