PREFACE 



In writing this small volume I have endeavoured to 

 explain the phenomena of immunity and make the 

 explanation as clear of conception as possible. My 

 chief object in producing this work is that it may be 

 a small means of stimulating the veterinary prac- 

 titioners of this country to take greater advantage of 

 the modern means of treating disease by the various 

 biological products, now at. their disposal. In this 

 branch of medicine we hold a distinct advantage 

 over the medical profession, inasmuch as we have a 

 greater freedom in applying biologies in the treat- 

 ment and diagnosis of the various diseases to which 

 the domesticated animals are subject ; also in serum 

 treatment we have the advantage that the serum 

 employed is very often obtained from the same species 

 of animal as the one on which we are employing it. 

 In other words, the serum is homologous. A great 

 drawback in serum treatment of human patients is 

 the fact that the immune bodies, or amboceptors, 

 contained in immune serum obtained from the lower 

 animals does not readily combine with the complement 

 present in human serum, hence the maximum benefit 



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