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. coloradensis, 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 large 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 "Greycliff," 2J 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 
