120 ANNUAL EEPOETS OF DEPARTMENT OP AGRICULTURE. 



A man was sent to investigate an outbreak of the so-called "big- 

 neck " of calves, which was reported by the Forest Service as being 

 prevalent in the Methow Valley, in northern Washington. The in- 

 vestigator arrived too late to find suitable material, as the calving 

 was largely over for the season. 



SWAMP FEVER OR INFECTIOUS ANEMIA OF HORSES. 



Experiments in the diagnosis of swamp fever have been continued, 

 particular attention having been given to the procuring of an antigen 

 that will permit the diagnosis of suspected cases by means of labora- 

 tory procedures, though no satisfactory method has yet been dis- 

 covered. A special structure has been erected for use in investiga- 

 tions relative to transmission by insects. Exposure tests have been 

 made with Tabanidse flies, but no transfer of swamp fever from horse 

 to horse has yet occurred through this means. 



The experiments of Seyderhelm and Seyderhelm for determining 

 the poisonous properties of cestrin, an extract from bots, have been 

 repeated, in view of the conclusion of those investigators that swamp 

 fever is due to bots. In none of the experimental cases of the bureau, 

 however, have bets played any part Avliatever. An extract was made 

 by grinding bots in sterile saline solution and filtering, and this 

 filtrate was tested on washed-blood corpuscles to determine whether 

 it might contain some form of hemolysin. The experiment gave 

 negative results. Donkeys injected with the extract prepared from 

 the bodies of bots showed no harmful effects aside from slight tem- 

 porary uneasiness. 



EXAMINING CATTLE REACTING TO THE TUBERCULIN TEST. 



The examination of glands and other tissues from cattle that have 

 reacted to the tuberculin test but in which no visible lesions of tuber- 

 culosis could be discovered at time of autopsy, has been continued. 

 Specimens from 42 reacting cattle of this class were examined by 

 laboratory methods for the presence of tubercle bacilli, and tubercle 

 bacilli were found in 15. This proportion is much lower than usual. 



WHITE SCOURS IN CALVES. 



The relationship between white scours and pneumonia of calves, 

 the tendency of the blood from affected calves to react to the aggluti- 

 nation and complement-fixation tests, and the possible relationship 

 between the two diseases mentioned and abortion of cattle have been 

 given extensive study, but no conclusion has been reached. INIany in- 

 quiries have been received concerning white scours in calves, and each 

 has been answered with directions for improving the sanitary sur- 

 roundings of the stables in which the stock was kept. 



RABIES. 



Because of the necessity of confining examinations for rabies to 

 animals in the immediate vicinity of Washington, a smaller number 

 than usual of suspected cases were received. Eighty animals were 

 submitted for laboratory diagnosis, and of these the diagnosis was 

 positive for 36 dogs, 2 cows. 2 cat^ and 1 hog, a total of 41 positive 

 cases. 



