LOCOWEBD DISEASE OF SHEEP 423 



Oestrus ovis infection. Aside from the microscopic studies of the nasal 

 mucous membranes and cervical lymph glands, detailed in the autopsies at 

 the end of Section C, my studies emphasize only two points with regard to 

 Oestrus ovis infection; first, that this parasite is a source of danger to 

 Western sheep; second, that the severity of the symptoms produced by the 

 parasite depends most intimately upon the general condition of the animal, 

 and upon the amount of nutritious food which it receives. 



It is of interest to observe that the Sarcocystis tenella was present in 

 practically every case in which the microscopic examination was made ex- 

 cept in the case of lambs only 3 or 4 months old. It is, however, not gener- 

 ally regarded as a dangerous infectious agent, although according to J. 

 Fiebiger, (Die tierischen Parasiten der Haus-und-Nutztiere; 1912, p. 113-119) 

 during one year IJ per cent of sheep at Budapest were condemned as unfit 

 for food on account of infection with this parasite. 



No special remarks are required concerning the lung and stomach worms, 

 for parasites of this type are known the world over. It is to be noted how- 

 ever, that this report together with the recent work from the Bureau of 

 Animal Industry shows that the semi-arid condition of the general grazing 

 grounds in the West is no protection against the spread of several dangerous 

 parasites, when the bed grounds, watering places, etc., are allowed to 

 become polluted, and to remain so. 



B. REVIEW OF RECENT PUBLICATIONS DEALING WITH LOCOWEED DISEASE. 



The office of the Poisonous Plant Investigations in the Bureau of Plant 

 Industry continued the study of locoweed disease, after the conclusions 

 which I drew from the field work of 1903 and 1904 had been submitted. 

 A double-headed campaign was launched, in which Dr. Albert C. Craw- 

 ford {loc. cit.) conducted investigations designed to test the poisonous 

 action of the locoweed under laboratory conditions and to ascertain the 

 nature of the poisons obtained, while Dr. C. Dwight Marsh {}oc. cit.) car- 

 ried out experimental studies of the loco problem in the field. 



After a scholarly review of the literature, Crawford details his own 

 elaborate experiments, which led him to conclude that the symptoms of 

 loco poisoning can be reproduced in rabbits by feeding them extracts of 

 certain loco plants; that the symptoms in the rabbits which he studied 

 were due to the barium in the locoweed extract; that there may be other 

 poisonous principles in locoweeds from other regions, and that locoweed 

 grown on some soils contains no barium and is not active. 



As Dr. Crawford did not test the locoweed grown in the region where 



