260 ANNUAL EEPORTS OF DEPARTMENT OF AGRICULTURE. 



other parts of the West and is no more likelj'^ to produce it in these 

 regions; and gaseous emanations i^robably have nothing at all to do 

 with it, as emanations of gas have never been proven even to exist. 

 But climatic conditions of a definite character, in combination with 

 certain plants, probably do have the necessary influence to engender 

 the disease, and from observations made tliis year it would seem that 

 the drinking water had a contributing influence. 



In reviewing the literature of plant poisoning of animals one is 

 struck with the great similarity of this disease to that condition 

 known as fagopyrismus, a disease of the skin and subcutaneous tissues 

 produced by the eating of buckwheat, but requiring the direct rays of 

 the sun to act in conjunction therewith. With this idea in view, an 

 opportunity was afforded at Christianburg, Utah, to put this theory 

 to a test, at least so far as the atmospheric conditions are concerned. 

 In less than two hours three different bands of sheep, 3 to 5 miles 

 apart, all exposed to the same atmospheric conditions and grazing 

 on the same kinds of plants, developed many cases of bighead. All 

 of them had been watered that morning in the Sevier River or in the 

 in'igation ditches flowing from that river. The first band to water 

 and the one farthest away from the stream at the time the sun began 

 to operate had the largest number of sheep affected. This band of 

 sheep had been shorn and w^as being hurried along on its way to the 

 home lambing grounds. The other two bands were not yet shorn 

 and were being moved more slowly. Several other bands subjected 

 to very nearly the exact conditions on other days developed cases of 

 bighead. 



It seems probable that poisonous properties in a certain plant or 

 plants, in combination with certain conditions, may be the causative 

 agent of the disease, and several plants are now under investigation. 



GLANDERS. 



A great number of specimens, principally nasal swabs, from sus- 

 pected cases of glanders have been received at the laboratory for 

 diagnosis. The usual bacteriological methods were employed for the 

 determination of the disease. 



Besides these routine examinations of suspected cases, experiments 

 were conducted by which an early and reliable diagnosis of latent 

 cases of glanders could be made. In many glandered horses the 

 clinical symptoms of the disease are manifested only at a late stage 

 or not at all, and such unsuspected latent cases must Ije considered as 

 dangerous in spreading the disease. The mallein and agglutination 

 tests both have their deficiencies, and a more reliable method of 

 detecting incipient and latent cases is very desirable. Following the 

 suggestion of a European correspondent, the Bureau is conducting 

 experiments with a precipitation method for the diagnosis of 

 glanders, and the results so far obtained are exceedingly promising 

 and indicate that with its aid an early diagnosis of suspected cases 

 will be possible not only in laboratories but in the field as well. 



ANTHRAX. 



In controlling outbreaks of anthrax it is the general practice to use 

 Pasteur vaccines for the purpose of preventing the spread of the in- 



