MEXICAN WHOELED MILKWEED AS A POISOlSrOUS 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 tliat antler range 

 conditions the dosage, in the majority of cases, would bo larger. 



WJwle plant. — Table 4 shows the dosage when the animals received 

 the whole ])lant. 



Table 4. — Dosage of A. mexicana, whole plant. 



Animal. 



Sheep 568 

 Sheep 575 

 Sheep 680 



Quantity 



fed per 100 



pounds of 



animal. 



Pounds. 

 0.882 

 1.058 

 1.235 



Result. 



Animal. 



I Quantity 

 fed per 100 

 poimdsof 

 animal. 



Sickness, 

 do. 

 do. 



Sheep 590. 

 Sheep 595. 



Pounds. 

 1.543 

 1.323 



Result. 



Death. 

 Do. 



