COCKLEBURS AS POISONOUS PLANTS 15 
Of the other organs the spleen and lymph glands appear to have 
shown the effects of a mild irritant. The lungs were characterized 
rather by a lack of blood than by congestion. This may have been 
due largely to the removal, from the general circulation, of the con- 
siderable quantity of blood which was accumulated in the liver. 
TOXIC AND LETHAL DOSAGE 
As is shown elsewhere, the plant was found to be poisonous only 
in the younger stages ; the largest part of the experimental work was 
done, therefore, on that stage of the plant which has been designated 
as the young cotyledon stage. This means the stage of the plant up 
to the time the first pair of leaves is partially formed. In gathering 
the plant for experimental purposes, especially during the later feed- 
ings, great care was taken to get it as young as possible. Plants in 
which the first pair of leaves was much developed were not ordinarily 
used. In the following discussion of dosage, only plants of this age 
are considered. 
In the experiments on pigs the smallest toxic dose was 0.736 per 
cent of the weight of animal in pig 20; pig 10 was made sick on 
0.895 per cent. The smallest lethal dose was 1.496 per cent of ani- 
mal, in pig 18. When no remedy was given and the plant was fresh, 
the largest dose given without effect was in the case of pig 20, July 
11, 1921, being 1.521 per cent. (Pig 12 received June 13, without 
effect, 2.856 per cent of its weight. The plant in this case, however, 
was probably older than the young cotyledon stage.) 
In general, then, it may be stated that the lethal dose for pigs 
is about 1£ per cent of the weight of the animal, and that the toxic 
dose may be as small as half of that quantity. 
Sheep 636 was killed by 1.513 pounds per hundredweight of ani- 
mal, while sheep 631 and sheep Til ate 1.477 pounds with no harm. 
So far as these experiments go, it would appear that the plant is 
about equally toxic to pigs and sheep. 
Cattle 945 was killed by 2.911 pounds per hundredweight of ani- 
mal, while cattle 970 received 2.801 pounds per hundredweight of 
animal with no effect. It seems probable from these results that the 
toxic and lethal dose for cattle is about 3 pounds per hundredweight 
of animal, and that it takes about twice as much to poison cattle as 
it does to affect pigs or sheep. 
With the chickens the feedings gave no definite results as to the 
toxic and lethal doses. Chicken 38 on two dates, a month apart, re- 
ceived 6 per cent of its weight and was not affected. Chicken 33 was 
fatally poisoned by two doses of 6 per cent on two successive days. 
In the autopsy of chicken 33 the crop was found still distended by 
a mass of Xanthium which was thought to be fully equal to the 
quantity given on the second day of the feeding. While the data 
are insufficient for a definite statement, these experiments indicate 
that the toxic and lethal dose is between 6 and 12 per cent of the 
animal's weight, with the probability that it is much nearer 6 than 
12. It is evident that chickens are much less susceptible to Xanthium 
poisoning than are pigs, cattle, or sheep. 
The relative toxicity of different parts of the plant is discussed on 
page 20. 
