788 



THE AMERICAN NATURALIST 



[Vol. XL 



A New or Altered Food Supply 



Poisonous Plants— Vlants which are fatal to some Herbivora 

 are innocuous to others. Linnseus in his Tour in Scania tells 

 us, as cited by Lyell ^ "that goats were turned into an island which 

 abounded with the Agrostis arundinacea, where they perished 

 by famine; but horses which followed them grew fat on the same 

 plant. The goat, also, he says, thrives on the meadow-sweet and 

 water-hemlock, plants which are injurious to cattle." ^ 



We must be extremely cautious not to substitute artificial con- 

 ditions or those brought about by the agency of man for purely 

 natural conditions. In speaking of the deaths caused by the 

 twenty-five species of stock-poisoning plants found in Montana, 

 Chestnut^ observes: "But all these causes operate much less 

 effectively against buffaloes and other ruminants in the wild state 

 for, in the first place, being bred there under perfectly natural 

 conditions, and being abundantly able to roam over long distances 

 in search for food and water, they naturally reject all but the best 

 and most wholesome diet. Then in the winter they migrate to 

 the south, where the conditions for their existence were more 



favorable Besides, it would require a large quantity of any 



of the common poisonous plants to kill an animal of such size." 



Observations in South Africa * give similar results. The 

 * chinkerinchee' plant (Ornithogalum) is poisonous to horses, 

 and one of the ragworts (Senecio) is an irritant causing cirrhosis 

 of the liver in cattle and horses. Other plants which give trouble 

 are tulps (species of ^loraea). The losses are chiefly among 

 cattle not accustomed to the country, or amongst very hungry 

 trek cattle. 



It is true, first, that animals gcneralK l.iir not invariably learn 

 to avoid poisonous plants, second, tliut tluy iH-conie more or less 

 immune to their deleterious effects, third, that often it is solely 



' Principles of Geology, vol. 2, p. 440, 1872. 

 2 Ibid., vol. 7, p. 409. 



'"Some Poisonous Plants of the Northern Stock Ranges." Yearbook 

 Dept. Aorinilturc for 1900, Washington, pp. 308-309. 



* Kindly communicated by Charles P. Lounsbury, of the Department of 

 Agriculture, Cape of Good Hope. See Agricultural Journal, February, 1906. 



