EEPORT OF THE SECRETARY OF AGRICULTURE. 19 



This is regarded as proof that the suspected serum actually was 

 infected. Why the standard tests used on 61 animals failed to reveal 

 this fact is a matter for scientific investigation, and the bacteri- 

 ologists of the department are at work upon the problem. At 

 the time of manufacture one-half of 1 per cent of carbolic acid 

 was mixed with the serum as a preservative. It is now believed 

 that the acid, acting as a germicide, may have attenuated or par- 

 tially destroyed the virus so that tests previously considered 

 safe failed to establish the presence of the infection. It also is 

 possible that the virus, instead of being disseminated throughout 

 the entire mass of serum, may have become agglutinated. This has 

 been known to occur with germs of other diseases. The result 

 would be the formation in the fluid of isolated clumps of foot-and- 

 mouth disease virus, while the bulk of it remained free from these 

 tiny masses. If this occurred it is obvious that certain animals in- 

 oculated with the serum would develop the malady and others would 

 escape. Up to the present time the germ has not been identified, 

 although the scientists of Europe have studied the disease exhaus- 

 tively for many years. 



Experiments are being prosecuted vigorously in the department 

 with a view to discover a means of treating serum at the time of its 

 manufacture which will kill the virus of foot-and-mouth disease. 

 The results so far attained are promising, and the department hopes 

 that a successful method soon will be evolved. In the meantime all 

 infected serum in the hands of the manufacturer, as well as all 

 other suspected serum manufactured in Chicago, has been destroyed. 

 Furthermore, the department is prohibiting the shipment of serum 

 from licensed establishments in the districts under quarantine for 

 foot-and-mouth disease. 



Appraisements of diseased animals. — In the handling of the prob- 

 lem difficulties arose because of the fact that the department in 

 making appraisements of diseased animals did not feel author- 

 ized to take into consideration their breeding value. In some 

 cases fine herds were involved. In all the discussions of the matter 

 before the Agricultural Committees of the Congress the beef or dairy 

 value was indicated as the basis for appraisal, and in former out- 

 breaks this basis was used. The suggestion was made that the 

 department be authorized to take breeding value into consideration; 

 but the Congress, in making an appropriation to reimburse the 



