VACCINE-THERAPY 199 



hereditary, and we know horses with long necks, narrow 

 intermaxillary spaces, long backs, narrow chests, etc., are 

 all liable to become roarers. But this point does not 

 interest us here so much as the fact that some animals 

 inherit in a pronounced degree a defective resisting-power 

 to bacterial invasion. 



We know some horses are more predisposed to the disease- 

 producing effects of the virus of strangles and influenza 

 than others, one animal suffering slightly or not at all, and 

 another severely. The protective antibodies of the one are 

 more resistant than in the other, and we are of opinion that 

 it is an inherited deficiency of the antibodies which largely 

 accounts for the practical conclusions of roaring appearing 

 most often in certain strains, and from one generation to 

 another. 



The Drain of Antibodies through the Milk-Supply as 

 a Probable Predisposing Cause of Tuberculosis. 



On p. 168 we stated our belief that every animal has the 

 power of resisting the bacilli of tubercle, some to a greater 

 degree than others. In such a complex mechanism as the 

 animal body, provided as it is with a variety of protective 

 bodies, many of which are little understood, it may be that 

 more than one antibody is deficient, and it is possible a 

 variety of forces are at play to account for this deficiency. 



We know milch cows are more prone to tuberculosis 

 than any other class of our domesticated animals. More- 

 over, some strains appear to be more predisposed to the 

 disease than others, and we invariably find the deeper the 

 milker the greater the predisposition to tubercle. 



The pertinent question may here be asked, Why should 



this be ? 



The depletion of the system through the milk-supply 

 undoubtedly accounts for a lowering of the vital forces, 

 and thereby making the animal a fit subject for bacterial 

 invasion. But why should the physiological act of lactation, 

 and even excessive lactation, predispose the animal to 

 tuberculosis ? Such a normal act should not disturb the 

 metabolism, and make the subject a suitable medium for 

 bacterial growth. 



It is, therefore, not enough to say the vital forces are 

 lowered by milking. There must also be a drain upon the 



