PASTORAL AND AGRICULTURAL BOTANY 



attacks of dyspnoea (Fig. 18). The toxic dose varies according to the 

 conditions of feeding. In drenched animals, it may be put at about one- 

 half a pound for an animal weighing a hundred pounds and in fed animals 



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PIG. 19. Curve of respiration of sheep No. 174 fed on Death Camas, Zygadenus 

 venenosus. The sheep was drenched at 12 o'clock noon and died at 11.15 P.M. The 

 respiratory rate rose to 200 between 2 and 3 o'clock, when the animal had one of the 

 spasmodic struggles for breath. It then fell to g and remained low, with comparatively 

 slight variations, until the time of death. (After Marsh, C. Dwight, Clawson, A. B. and 

 Marsh, Hadleigh: Zygadenus, or Death Camas, Bulletin 125, U. S. Department of Agri- 

 culture, 1915, p. 27.) 



it varies from 1.6 pounds to 5.6 pounds (Fig. 19). The poisonous principle 

 is an alkaloid or alkaloids, allied to veratrin and cevadin. Sick animals 

 should be kept quiet as if this is done there are chances of recovery. No 

 satisfactory medical remedy has been discovered for camas poisoning. 



