MEXICAN WHORLED MILKWEED AS A POISONOUS PLANT. 
13 
lymph space, but in some instances they had penetrated into the 
surrounding tissue. Pericellular lymph spaces, in many if not most 
instances, were enlarged. The nerve cells had undergone fatigue 
changes similar to those found in the A. pumila and A. galioides 
cases. This consisted in a breaking up of the Nissl bodies or a 
marked reduction in the chromatin content of the cell. 
In general the pathological conditions of the A. mexicana 
cases are the same as those found in A. galioides and A. pumila 
poisoning, and consist mainly of capillary congestion and degenerative 
changes in certain tissues. Areas of congestion were found in the 
liver, kidneys, heart, muscle, lungs, thymus, and mucosa of portions 
of the intestines. The cells of the liver, kidney tubules, heart muscle, 
intestinal glands, and certain nerve cells showed degenerative changes 
which may probably be accounted for by excessive functional 
activity. Fatigue effects were most apparent in the heart-muscle 
fibers and nerve cells. The presence of an abnormal number of 
leucocytes in the liver, intestinal mucosa, and lungs is probably due 
to the degenerative changes of the tissue cells. 
Degeneration of hepatic cells, epithelium of kidney tubules, and 
intestinal mucosa appears to be more pronounced in the A. mexicana 
cases than in those animals killed by A. galioides. On the other 
hand the degeneration and capillary congestion of heart muscle, con- 
gestion of the nervous system, and fatigue effects on the Purkinje 
cells of the cerebellum were much more pronounced in the A. galioides 
cases. 
The changes found in the tissues of the A. pumila cases correspond 
very closely to those described for the A. mexicana cases. The effects 
of these two species of plants would appear to be practically the 
same, but those produced by the more toxic A. galioides differ slightly 
in degree. 
TOXIC AND LETHAL DOSES. 
The balling gun was used in all the experimental work from which 
the dosage was computed, so that the animals probably received the 
material in a somewhat shorter time than they would when feeding 
on the range. It would be expected on this account that under range 
conditions the dosage, in the majority of cases, would be larger. 
Whole plant. — Table 4 shows the dosage when the animals received 
the whole plant. 
Table 4. — Dosage of A. mexicana, whole plant. 
AnimaL 
Quantity 
led per 100 
I pounds of 
animal. 
Pounds. 
Sheep 568 1 0. 882 
575 ! 1.058 
580 ' 1.235 
Result. 
Sickness, 
do. 
do. 
Animal. 
Sheep 590. 
Sheep 595. 
Quantity 
fed per 100 
pounds of 
animal. 
Pounds. 
1.543 
1.323 
Result. 
Death. 
Do. 
