144 MANUAL OF POISONOUS PLANTS 



and ptomains react in a similar manner. The volatile alkaloids, represented by 

 nicotin and coniin, possess disagreeable odors suggesting in part that of am- 

 monia. The solid alkaloids, represented by strychnin, morphin, are odorless, but 

 have a bitter taste, often very characteristically bitter. 



Physiologically, the alkaloid is quite generally a very active intoxicant, acting 

 directly on the nervous tissues and producing results all the way from the atonic 

 to the strongly tonic effects. The extreme effects are seen in the muscular 

 excitation of strychnin and the depressing action of morphin, or, in the heart 

 stimulation of atropin, and the depressing effects of cocain. 



OCCURENCE OF THE ALKALOIDS. 



The alkaloids are peculiarly a plant product and probably may be regarded 

 as a protective agency to preserve a given species of plants. They are deposi- 

 ted in various parts of the plant but commonly in the seeds. The seeds con- 

 taining, as they do, the vital parts of annual plants, (and also perennials) are 

 protected from destruction by micro-organisms and by animals using them for 

 food, by the intoxicating property, just referred to. A similar case is that of 

 the glucoside amygdalin, as found in the seeds of several of the Rosaceae. 

 The enzyme present in the seed, under proper conditions of temperature and 

 moisture, decomposes it into glucose benzaldehyde and hydrogen cyanid or prus- 

 sic acid, this latter compound acting as the intoxicant. 



The alkaloids are not widely distributed in the plant world, although they 

 are found in several orders or families of plants. Three families are especially 

 characterized by the presence of alkaloids, namely, the poppy family or Papav- 

 eraceae, night shade family, Solanaceae, and the Rubiaceae. 



The basic property of the alkaloids suggests the probability of their occur- 

 rence in combination with acidic compounds more or less characteristic of the 

 plants in which they are found. In some cases the so-called alkaloid appears 

 to be similar to glucoside, i. e. it can be hydrolyzed. For example, cocain can 

 be hydrolyzed into ecgonin, C^H^^NOg, benzoic acid, CgH^CO^H and methyl 

 alcohol. Others are real glucosides like digitalin and solanin. It is undoubtedly 

 true that the latter two should not be classed with true alkaloids, but with the 

 glucosides, and are like caffien theobrdmin in this sense, i. e., that they are 

 substances that have been classed with the alkaloids on superficial grounds, such 

 as bitter taste, but really have no close chemical relation with them. Caffein 

 and theobromin are now known to belong with the purin compounds. The purin 

 compounds are basic, and hence their classification with the alkaloids. 



The acids with which the alkaloids are often united are somewhat common 

 in plants, or in a few cases they are characteristically found in combination with 

 the given alkaloid, e. g., meconic acid in combination with morphin in opium, 

 or aconitic acid united with aconitin. Other acids form compounds with the 

 alkaloids in the various plants in which they are found. Among these acids 

 are tannic, citric, malic and quinic. The combinations are easily broken up by 

 strong bases, like potassium or sodium hydroxid, and in this way they may be 

 separated from the acids. Since the true alkaloids are generally soluble in 

 water while alkali salts of the acids are not soluble, the alkaloids may be 

 separated by treatment with potassium or sodium hydroxid and filtering out the 

 insoluble alkaloid. They are then further purified by the formation of the 

 soluble salt and re-precipitating the alkaloid by an alkali. The alkaloid is then 

 dissolved by the appropriate solvent and crystallized. Again it is interesting 



