88 MANUAL OF POISONOUS PLANTS 



the quality of the grain. Why should it not also influence the poisonous con- 

 stituents of the plant? Cornevin mentions that soil affects the color of Digitalis, 

 it being much paler when grown in calcareous than when grown in granitic 

 soil. 



RELATED SPECIES AND TOXIC SUBSTANCES. In some cases the 

 same toxic substance is widely distributed in different families of plants. On 

 the other hand closely related plants frequently have entirely different amounts 

 of toxic substances. The bitter and sweet almond illustrate this in a very 

 marked degree, the bitter almond having considerable amounts of the glucoside 

 amygdalin, while the sweet almond is entirely harmless. 



Frank Rabak x has made an investigation of the amount of the chemical 

 substances found in the kernels of the fresh apricot and plum, in which it ap- 

 pears that the amount of hydrocyanic acid by per cent contained in these plants 

 is as follows :- 



Per Cent 

 Peach ......... 2.20 



Apricot . . . . . . . . .2.40 



Apricot ......... 2.05 



Prune . . . . . . . . .1.75 



Bitter Almond . . . . . . . .4.80 



According to Dohme and Engelhardt 2 the thin green or young bark of 

 Prunus serotina is richer in hydrocyanic acid, than the dark brown or older 

 bark. 



It may be interesting to note that certain species of Cacti are used for 

 stock food, 3 and others contain powerful drugs. For instance, the Mescal 

 Bean, which is derived from several species of Anhalonium which contain pel- 

 iotin, is a narcotic of considerable potency. 4 



According to Dr. Peinemann 5 the alkaloidal-content of Datura varies as 

 follows; the seeds, 0.541 percent.; root, 0.315; leaves, 0.41 percent, of atropin, 

 The Datura alba is richer in alkaloids than the native species, D. Stramonium. 



Dunstan and Henry 6 are authorities for the statement that two forms 

 of Mandrake, the American (Podophyllum peltatum} and the Indian (P. emodi), 

 produce the same principle podophyllotoxin C 1( .H 14 O 6 a strong purgative and 

 also the so-called podophyllin which consists of a resin. The podophyllotoxin 

 occurs in the Indian plant from 9-12% and in the American plant from 4-5%. 



DISTRIBUTION OF CHEMICAL SUBSTANCES. The same chemical sub- 

 stance is frequently found in plants that are not closely related. For instance, 

 Edward Kremers and many other pharmaceutical chemists have found the 

 essential oils in widely separated families, and Greshoff states that a leaf of 

 Five-finger (Potentilla davurica of China) which is closely related to our 

 shrubby Cinquefoil (P. fruticosa) produces a powerful odor of roses. Ger- 

 anoil occurs, for instance, in the young foliage of willow and many other plants. 



The substance berberin is found in a large number of plants like the Bar- 

 berry, the Mandrake, Twin Leaf (Jeffersonia diphylla), Meadow Rue (Thai- 

 ictrum flavum), Toddalea aculeata, Hydrastis canadensis, Argemone mexicana, 

 etc. 



1 Bull. U. S. Dept. Agr., Bur. Plant Industry. 133. 



2 Pharm. Review. 14:13. 



3 Griffiths and R. F. Hare, The Tuna as Food for Man. Bull. U. S. Dept. Agrl. Bur. 

 Plant Ind. 116. 



4 Pharm. Review. 14:153. 



5 Pharm. Review. 14:233. 



6 Proc. Chem. Soc. 189:42-44. 



