Chemical and Physical Papers. 51 



plants, made in the laboratory under the proper conditions, pro- 

 duced fatal effects. But what was the nature of the poison? It 

 had been proven a nonvegetable substance. What other poison 

 could a vegetable secrete ?" 



Chemical experiments conducted along with the pharmacologi- 

 cal experiments of Marsh and Crawford resulted in a very impor- 

 tant discovery, namely, that if the ashed plant was extracted with 

 sulphuric acid the solution proved inactive to rabbits. In other 

 words, the substance removed by the use of sulphuric acid seemed 

 to be the active material. Such a reaction would point to one of a 

 group of important substances which a plant would be liable to 

 assimilate Accidentally, Crawford found that Spengel had re- 

 ported the presence of barium in one of the species of astragalus, 

 a closely allied plant to the loco, and also found recorded in chem- 

 ical literature that barium had been found in a number of other 

 plants by other chemists. Guided by this indication pointing to a 

 solution of the problem, and having well-grounded suspicions that 

 the cause of the poison might be after all an inorganic poison, and 

 having suspicioned barium as the inorganic element, feeding ex- 

 periments with barium were conducted upon animals in the labo- 

 ratories. These were accompanied with positive results. It was 

 found, for example, that one gram of barium carbonate would kill 

 a dog in eight hours. It may well be stated in passing that it is 

 well known that barium carbonate has been employed as a rat poi- 

 son, and its toxic qualities upon lower animals have been well 

 established. Recently the high toxicity of barium has been rec- 

 ognized by a writer on pharmacology. The peculiar effect of its 

 salts upon the circulation, upon the heart, upon the nervous sys- 

 tem and upon the blood pressure are symptoms giving evidence of 

 this; and if barium is contained in the soil and is absorbed by the 

 plants, the plants ingested and the barium content assimilated in 

 the circulatory system, it would produce, very gradually, the symp- 

 toms recognized as the loco disease. But the physiological action 

 of this inorganic element was thoroughly worked out (for the first 

 time) by Crawford in the pharmacological laboratory, and the con- 

 nection with it and loco well established — and thus the mystery of 

 the Toco poisoning seems to be finally solved. The work of Marsh 

 and Crawford is by far one of the most important issuing from the 

 laboratories of plant and animal industry, located in Washington. 



One of the mysteries connected with the problem was that loco 

 in certain pastures was nontoxic. This phenomenon has also been 

 accounted for by the above investigation. It has been shown by 



