ZYGADENUS, OR DEATH CAMAS. 35 



sheep and would indicate that the toxic dose for cattle, computed 

 in terms of the weight of the animal, does not differ materially 

 from the toxic dose for sheep. 



COMPARATIVE TOXICITY OF DIFFERENT SPECIES OF ZYGADENUS. 



In the course of the experiments, four species of Zygadenus were 

 used, Z. venenosus, Z. elegans, Z. paniculatus, and Z. color adensisj by 

 far the greater part of the work being done with Z. venenosus. The 

 number of experiments with Z. elegans and Z. paniculatus was very 

 small, and the material, especially in the case of Z. paniculatus, had 

 been shipped a long distance, so that there was some question of the 

 water content of the plant. Apparently, however, Z. elegans and Z. 

 paniculatus do not differ materially in toxicity from Z. venenosus. 

 Z. coloradensis, however, produced no toxic effects whatever with 

 the exception of slight symptoms in one sheep, although the plant 

 was fed in quantities several times as great as the toxic dose of Z. 

 venenosus. 



It is evident that in the feeding of cattle with Zygadenus coloraden- 

 sis at Mount Carbon in 1909, the results of which are given in Table I, 

 the quantities fed were too small to produce results, even if the 

 plants were as poisonous as Z. venenosus. In the experiment of 

 1910, however, a Jarge quantity was fed, and sufficiently large 

 quantities in single days to produce symptoms of poisoning if the 

 plant were as toxic as Z. venenosus. 



In this connection it should be added that Dr. C. L. Alsberg made 

 a laboratory examination of the Colorado plants and found in them 

 a very small quantity of alkaloid. It would appear, then, that the 

 form which is identified by some botanists as Z. coloradensis contains 

 the same toxic substance as the other form, but that this substance 

 is present in so small a quantity that it is unlikely that it ever 

 produces toxic effects on domestic animals. While it is not in the 

 province of this paper to discuss the systematic relations of plants, it 

 may be suggested that this difference of toxicity between Z. elegans 

 and Z. coloradensis may indicate a valid specific distinction between 

 these two forms which are so closely related that by some botanists 

 they are considered identical. 



DOES TOXICITY VARY WITH LOCALITY? 



The collections of Zygadenus venenosus with which experiments 

 were made were obtained at the "Station" (by which is understood 

 the region within a radius of 2 miles of the station), at an elevation 

 of about 4,050 feet; at "GreycliftY' 2i to 3 miles distant from the 

 station, at an elevation of about 3,920 feet; and at "Cabin Corral" 

 and "George Hughes's " (locations from 4 to 7 miles from the station), 

 at an elevation of something over 5,000 feet. Material of this species 



