A SPECIFIC INFECTIOUS DISEASE 1 9 



had been thoroughh- washed in a i to looo solution of corrosive 

 sublimate. In all, there were eight samples of milk taken 

 from as many different cows. In six of the eight specimens 

 streptococci appeared in pure culture. In the other two cases 

 micrococci were associated with the streptococcus. In the 

 second outbreak, the milk from four diseased udders was drawn 

 with aseptic precautions directh- into tubes containing slant 

 agar and promptly sent to the laboratory where it was carefully 

 examined. From two cases pure cultures of streptococci were 

 obtained while those from the others were impure. The strep- 

 tococci obtained from the twelve cases appeared to be identical 

 and the clinical aspect of the disease in the different animals 

 was the same. 



In a dairy that was under close observation by Ward, one 

 cow was found to be troubled in one quarter of the udder with 

 an inflammatory process which produced thickened masses in 

 the blood-stained milk. From this milk a streptococcus was 

 isolated in pure culture. It could not be differentiated from 

 the one isolated from the cows in the outbreaks mentioned. 

 Another cow in this herd was found to have her udder per- 

 manently infected with a streptococcus. Another animal in the 

 same dairy suffers repeatedly from acute streptococcus mastitis. 



There are a large number of morbid conditions more or 

 less frequently encountered in domesticated animals which 

 seem to be due to infection of some kind but which are not 

 demonstrated to be of such an origin. These will continue to 

 be attributed bj- some to infection and by others to various gen- 

 eral causes until the truth concerning their etiology is revealed. 



S 13. A specific infectious disease. A specific infec- 

 tious disease is the result of the multiplication within the animal 

 body of a single species of microorganisms. The lesions may 

 be localized or general but the cause producing them is always 

 the same. Thus Bacterium anthracis will produce a disease 

 which is called anthrax, no other cause can produce it and no 

 matter how much the lesions may vary in different individuals 

 if they are produced by this species of bacteria the disease is 

 anthrax. It is clear, therefore, that there is no hard and fast 

 line between a simple (singlej wound infection and a recognized 



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