424 UNIVERSITY OF VIRGINIA PUBLICATIONS 



my experiments were conducted, it cannot be determined, except by a 

 special study, whether he would have placed these particular locoweeds in 

 the barium-containing, actively poisonous group, or in his inactive group 

 free from barium. But this much is certain; the sheep which ate this loco- 

 weed freely for the greater part of the fifty-three days of the experiment 

 presented neither the symptoms, nor anatomical changes which Crawford 

 gives as characteristic of barium poisoning. A recent publication by Als- 

 berg and Black weakens the force of Crawford's conclusions. These writers, 

 (Bureau of Plant Industry, 1912, Bull. 246) as the result of experiments 

 and other considerations which they record, are led to the convictit)n that 

 the toxicity of locoweeds in laboratory experiments is not due to barium, 

 and Marsh also (Bull. 246) concludes from studies in the field that typical 

 loco poisoning is not produced by barium feeding alone. Up to the present 

 no further laboratory studies have been published, and it now looks as if 

 Crawford's view as to barium cannot be maintained, but that his experi- 

 ments at least suggest that some locoweeds contain a poison of unknown 

 nature which other locoweeds do not contain. 



The second division of the attack upon the loco problem was under 

 the direction of Dr. Marsh who conducted feeding experiments upon a 

 larger and more thorough scale than had ever before been attempted. For 

 three seasons, 1905, 1906, and 1907, horses and cattle were fed upon loco- 

 weed in three camps established in Colorado and Nebraska. The animals 

 were observed during life, autopsies were performed on many of them, and 

 many other locoed animals, horses, cattle, sheep, and goats were examined. 

 Accounts of the experiments and of the results obtained appear in several 

 bulletins from the Department of Agriculture, and in reports from the Agri- 

 cultural Experimental Stations of Colorado and Nebraska which actively 

 cooperated in Marsh's work. From these accounts it is clear that Marsh be- 

 lieves that he has solved the loco problem, that he has proved that the 

 locoweed is poisonous, and that he has established symptoms and anatom- 

 ical changes which are together equally characteristic of locoweed intoxica- 

 tion. It is, however, difficult for a medical reader studying Marsh's reports 

 to follow him to his conclusions, for the data which he prints in his technical 

 report (Bull. 112), and elsewhere, do not always make it logically necessary 

 for the reader to come to the same conclusions that Marsh reached. This is 

 noticeable between pp. 47 and 72 in his review of cases, where it cannot be 

 seen by the reader that Marsh has always excluded other possible diagnoses 

 with sufficient fulness to justify his conclusions that the animals described 

 owed their maladies to the locoweed. This deficiency may be corrected 

 when he pubhshes in full his anatomic, microscopic, and bacteriologic stud- 



