12 BULLETIN 1240, U. 5. DEPARTMENT OF AGRICULTURE. 
Table 6. — Comparative toxicity of species of Zygadenus. 
[Minimum toxic dosage in pounds of plant per 100 pounds of animal.] 
Tarts of plant. 
Z. gra- 
mineu-. 
Z. pani- 
culatus. 
Z. ele- I Z. ren- 
gans. nosu s. 
Leaves, stems, and young fruit. . . 
Leaves and stems 
Fruit heads 
Seeds 
Leaves, stems, and buds 
Leaves, stems, and flowers 
Leaves, stems, flowers, and buds. 
Leaves, stems, flowers, and bulbs 
Bulbs 
0. 
.33 
.161 
.093 
.495 
1. 505 
1.9*4 
.07 
1.096 
1.323 
o. 74* 
» 2. 437 
i. 807 
1.97 
2.939 
493 
2. 373 
* No effect. 2 One case. 
From the experimental work on toxicity and the comparisons made 
in Table 6, it appears that Zygadenus gramineus and Z. venenosus are 
equally toxic and that these species are three times as toxic as Z. 
paniculatus and seven times as toxic as Z. elegans. 
COMPARATIVE LETHAL DOSE OF SPECIES OF ZYGADENUS. 
The minimum lethal doses of the four species of Zygadenus with 
which experiments have been made, expressed in pounds per 100 
pounds of animal, are as follows: 
Zygadenus gramineus 0. 544 
Zygadenus paniculatus 2. 5 
Zygadenus elegans 6. 153 
Zygadenus venenosus 2. 
So far as these figures go, it appears that the lethal doses of Zyga- 
denus paniculatus and Z. venenosus are, respectively, about 5 and 4 
times that of Z. gramineus, while that of Z. elegans is more than 11 
times that of Z. gramineus. 
The ratio between the toxic and lethal doses of the four species is 
a matter of considerable interest. This ratio of minimum toxic to 
minimum lethal dosage is as follows : 
Zygadenus gramineus About 4 to 5. 
Zygadenus paniculatus - About 1 to 2. 
Zydadenus elegans About 1 to 3. 
Zygadenus venenosus About 1 to 5j. 
That is, while the ratio of toxic to lethal doses does not differ 
widely in Zygadenus gramineus, Z. paniculatus, and Z. elegans, in 
Z. venenosus, which has practically the same toxic dose as Z. gra- 
mineus, the lethal dose is three and one-half times as great. The 
practical bearing of this ratio is that while Z. gramineus and Z. vene- 
nosus are about equally dangerous so far as making sheep sick is 
concerned, the chances of death are much greater in cases poisoned 
by Z. gramineus. As the actual minimum lethal dose is about the 
same in Z. paniculatus and Z. venenosus, it would appear that the 
chances of a fatal issue are about equally probable in these two species. 
