IS BULLETIN 12*74, U. S. DEPARTMENT OF AGRICULTURE 
In the case of pig 32 it is known that all the feedings were of the 
young plant, before the development of the leaves, and this animal 
repeatedly received a quantity slightly less than the minimum lethal 
dose, with no ill effect. Twice on two successive days it received a 
total of 2.6-45 per cent of its weight, while, with the exception 
of pig 12 on June 9. as has been explained, no other pig received 
mure than 1.521 per cent without toxic eri'ects. These cases make it 
fairly evident that Xanthium is not a cumulative poison, but that. 
on the other hand, it is rather rapidly eliminated. 
Inasmuch as several times, after a series of daily feedings, a single 
feeding much greater than the minimum lethal dose produced no 
symptoms, it seems probable that some toleration was acquired. The 
experiments were not sufficiently numerous so that a positive state- 
ment can be made of this fact, but it seems probable that this is the 
ca^e. 
ANIMALS POISONED 3Y COCKLEBUR 
The experimental work described in this bulletin was on swine. 
sheep, cattle, and chickens and demonstrated conclusively the poi- 
sonous effect of cocklebur on these animals. There was no work done 
by the writers on horses, but others have reported such cases of poi- 
soning. It is presumable that they would be affected if they ate the 
plant. As a matter of fact, horses are less liable than other domestic 
animals to be injured by any poisonous plants, because they select 
their feed with more care. The dosage would indicate that while 
chickens may be poisoned, under ordinary circumstances such occur- 
rences are rare. 
PART OF PLANT POISONOUS 
Experimental feedings were made not only of the whole plant in 
the young cotyledon stage but of seeds, roots, cotyledons, stems and 
roots, and plants with the cotyledons removed. It was found that 
plants above the young cotyledon stage were only slightly poisonous 
and these are therefore of no practical importance from the stand- 
point of the toxicology of the plant. ^Moreover, as the plants in the 
young cotyledon stage have no disagreeable taste, they are eaten quite 
readily. As the plants grow older the leaves develop a very bitter 
taste, and animals generally refuse to eat them. 
It was found that the seeds, removed from the burs and fed to 
some of the pig-, were much more toxic than other parts of the 
plant. Pig 10 was killed by 0/275 per cent of animal weight. Piu* 
1^ received 0.2535 per cent of animal weight with no effect. It seems 
probable from the experiments with pig 10 that the minimum toxic 
and lethal dose is not far from 0.275 per cent of animal weight, al- 
though ;tu animal may receive as much as 0.2535 per cent with no 
irent effect. 
Chicken : >~ was made sick on 0.22 percent of its weight, and chicken 
"'' died from the same dosage. So far a- these few experiments go 
appear to be more toxic to chickens than to | 
The feeding of plants having 2. 4. and 6 leaves was not attended 
with harm t*ul result, showing that the plant lo<e> its toxic proper- 
• . rapidly ;is ii develops from (lie cotyledon siajjv. So far as 
I he experiment.- indicate it would appeal- that the cotyledons have 
• bout the same toxicity as the whole plant iii the young cotyledon 
ge. 
