THE WOOLLY-POD MILKWEED. 13 
_ less marked in the liver and lymph glands. Effects of the irritant 
were also present in the loose connective tissues of most of the organs 
examined. 
TOXIC AND LETHAL DOSAGE. 
The smallest quantity that produced a toxic effect in sheep was 
0.1 pound per hundredweight of animal, in the case of sheep 651. 
This animal was fed by balling gun. As sheep 683, fed in the same 
way, received 0.2 pound with no positive symptoms, and sheep 662, 
0.21 pound with no effect, 1t would appear that 0.1 pound per 
hundredweight is about the minimum toxic dose, while an animal 
may receive twice as much with no untoward result. The smallest 
lethal dose was 0.22 pound per hundredweight of animal in sheep 670. 
It is evident that there is no very marked difference between the 
toxic and lethal doses. 
Of the two head of cattle used, No. 988 was made very sick on 
0.2 pound per hundredweight of animal, and No. 928 showed 
symptoms on 0.1 pound. It appears that, compared with the weight 
of animal, the dosage of cattle was practically the same as that of 
sheep. 
The plant is shown to be very poisonous. As compared with the 
whorled milkweeds, which are discussed in Department Bulletins 800, 
942, and 969, it has a dosage much like Asclepias galioides, 
COMPARATIVE TOXICITY OF LEAVES AND STEMS. 
Four of the experimental animals were fed with the stems of the 
plant. All the others received leaves. So far as this number of 
feedings is concerned, it appears that the stems and leaves are 
equally toxic. 
ANIMALS AFFECTED. 
The experimental work was with cattle and sheep and it is shown 
that both classes are susceptible to poisoning by woolly-pod milk- 
weed. There are no data in regard to its possible effect on horses; 
no reports of poisoning of horses have been received, but it is prob- 
able that they, as well as cattle and sheep, may be poisoned. 
All the experimental work was done with dried plant. It is evi- 
dent that the woolly-pod milkweed may be a dangerous element in 
hay, for in some localities it grows so abundantly that considerable 
quantities may be gathered with the hay. 
SUMMARY. 
Woolly-pod milkweed (Asclepias eriocarpa), a plant growing 
rather abundantly in parts of western California, has been suspected 
of being poisonous to sheep. It has been shown to be very poisonous 
not only to sheep but also to cattle. 
While animals are not likely to eat it except when other forage is 
scarce, it is dangerous because of its especially toxic character, for as 
little as 0.1 of a pound per hundredweight of animal may poison, and 
0.22 of a pound may cause death. 
