THE WHORLED MILKWEED AS A POISOlsrOUS PLANT. 21 



the water-soluble fraction, and the substance which causes the spas- 

 modic symptoms observed in animals. After a complicated manipu- 

 lation the last substance was obtained as a colorless, brittle, resinous 

 mass which has not yet yielded anything of a crystalline nature. It 

 melts indefinitely at about 60° C, is insoluble in water, aqueous acids, 

 and alkalies, is very soluble in alcohol, amyl alcohol, glacial acetic 

 acid, acetone, chloroform, ether, benzol, acetic ether, and pyridine. 

 It does not appear to be glucosidal. Further investigation, with the 

 object of determining its precise chemical nature, is in progress. 

 . This substance has been thorouglily tested upon guinea pigs and 

 produces the characteristic symptoms observed on the range, with the 

 typical lesions. 



Fresh samples of the plant were tested for the presence of volatile 

 poisons and toxic saponins, with negative results. 



PHAEMACOLOGICAL EEST3XTS. 



The pharmacological work was conducted according to the follow- 

 ing plan : Each of the various fractions resulting from the chemical 

 treatment of the plant extracts was administered through the mouth 

 to an animal. Extracts which contained much matter insoluble in 

 /'water were emulsified in that liquid with either acacia or mucilage of 

 Irish moss ; soluble extracts were given in water solution. Frequent 

 control animals served to exclude accident. 



The animals used were sheep and guinea pigs. The larger propor- 

 tion of the testing was done with the latter animals, which were 

 found to react excellently and characteristically to the toxins of the 

 plant, duplicating the symptoms observed in the experimental sheep 

 almost to the most minute detail. In indefinite cases the tests were 

 repeated upon several animals; 126 experiments in all were con- 

 ducted. As criteria in the work upon the guinea pigs were taken 

 the symptoms and pathological lesions exhibited by the experi- 

 mental sheep. By following this plan it was found possible to 

 exclude many of the plant constituents as innocuous or as not factors 

 in range poisoning and to locate definitely the fractions which con- 

 tain toxic substances. 



Three general and distinct types of intoxication were observed in 

 guinea pigs which were drenched with toxic fractions of extracts 

 from this plant. 



The first type closely resembles the typical cases of range poisoning 

 which follow the ingestion of the whole plant. This type of intoxi- 

 cation is produced by the resinous substance described above ; it com- 

 mences with a general weakness, the animal appears disinclined to 

 move about, and is soon narcotized. After an interval convulsions 

 appear, with the characteristic running movements in many cases 

 and the peculiar tendency to fall and lie always on the same side of 



