THE PRODUCTION OF POISON IN PLANTS 85 



Miss Alice Henkel in a paper on American Root Drugs 1 notes the im- 

 portance of collecting medicinal plants and drugs at the right time. The roots 

 of the American Hellebore (Veratrum viride) should be collected in the 

 autumn after the leaves are dead. Generally speaking the drugs contain more 

 of the medicinal virtues after the period of cessation of growth of the plant. 

 Dr. C- Mueller 2 calls attention to the fact that Colchicum is much better if the 

 rhizome is collected at time of flowering. On this point all authorities do not 

 agree. Cornevin who has made a study from month to month of the migration 

 of poison in plants such as the Laburnum found the following conditions : On 

 May 20th, 2 grammes of the dried leaves of Cytisus Laburnum, administered to 

 some carnivorous animal, were sufficient to induce vomiting. On June 10 (at 

 which time pods were forming) 4 grammes were required to produce the same 

 result. July 28 (when the pods were fully formed) 12 grammes were required. 

 September 28 (pods were beginning to dry) 20 grammes were required. 



The experiments show that at all periods the leaves were poisonous but 

 as the poison became concentrated in the pod the leaves became less toxic. 



Similar experiments resulted in demonstrating that while the poison con- 

 centrates in the pod it also loses toxicity as the season advances, enormous 

 doses taken from dried seed in October failing to produce death, while a 2- 

 gramme dose from a June pod proved fatal. 



CLIMATIC. Latitude has an influence upon the formation of poisons- 

 There are more poisonous plants in tropical regions than in colder regions. 

 Certain plants which are poisonous in temperate regions lose their poisonous 

 properties when taken into colder regions. Examples of this are aconite and 

 cherry laurel. 



It is difficult to make a comparison between the total number of poisonous 

 plants in tropical and temperate regions, but it is probable that the warmer 

 regions will show the greater number of poisonous species. 



It might be well, however, to note in this connection that the poisonous 

 properties of Rhododendron Chrysanthemum and R. catawbiense as well as of 

 Aconitum are developed in colder regions while such toxic plants as the calabar 

 bean (Physostigma venenosum), Strychnos nux-vomica, the Upas tree (An- 

 tiaris toxicaria) and numerous others are inhabitants of warm climates. 



It is well known that the sorghum grown in dry climates produces a 

 greater amount of a glucoside which is capable of being, converted into hydro- 

 cyanic acid than in more moist regions. Some writers even assert that in dry 

 seasons the drought depauperates the plant and that in the nodes there are 

 considerable quantities of potassium nitrate. 3 



Again Dr. Ludwig Bernegau notes that the amount of alkaloid in Cola 

 Nut varies considerably, it depending upon the source of the nut. 



With reference to the presence of alkaloids in different kinds of opium, 

 it is known that the Smyrna opium is of superior quality for medicinal pur- 

 poses. It is said to be superior to the opium obtained from India, which is in 

 part attributed to climatic conditions, and probably in part to the method of 

 collection. According to Blyth, the amount of morphin varies as follows : 



Crude morphin (containing about 7-10 of pure morphin). Highest, 12.30; lowest, 6.76; 

 mean, 9.92 per cent, which equals 12.3 per cent of the dried drug. 



1 Bull. U. S. Dept. Agrl., Bur. Plant Industry, 107. Farmers Bull. 188. 



2 Pharm. Review. 14:113. Die Natur. 44:550. 



3 An English writer, Pease, attributed the death of animals to this substance rather than 

 to the hydrocyanic acid. Pharm. Review, 15:208. 



