TRANSMISSION OF BOVINE TUBERCULOSIS. 203 



TRANSMISSION OF BOVINE TUBERCULOSIS. 

 By Noah Cresset, M. D , V. S., Ph. D. 



Given at Farmers' Institutes at Orono, Winthrop and Island Pond. 



Nowhere in the struggle of life, against the manifold causes of 

 disease, do we more effectually imperil our health and happiness 

 than in partaking of animal food of a suspicious character ; for the 

 relation of man to the lower orders of animals, which has caused so 

 much speculation among philosophers and naturalists on certain 

 zoological affinities, is equally interesting and instructive in 2l patlio- 

 logical point of view. The skeletal framework and internal organ- 

 ization of the higher mammalia are not only morphologically identical 

 with the structure of man, and thus subserve the same purpose in 

 animal econom}', but the blood is similar in chemical composition, 

 contains the same anatomical elements, and is subject to analogous 

 changes in disease ; hence the liability of transmitting to the human 

 subject some virulent blood-poison, through the medium of our ani- 

 mal sustenance. 



The sterling achievements in comparative pathology, which the 

 last decade has wrought relative to the germ theory, have not only 

 awakened new zeal among scientific men, both at home and abroad, 



but have necessitated the recognition of a biological factor in the 

 studv of the etiologv of many forms of disease. The results of 

 these researches have revolutionized in a great measure all previous 

 conceptions of the real nature of contagion ; and it has now been 

 conclusive!}' demonstrated by the concurrent testimony of competent 

 observers, that the disease-bearing germs of anthrax, tuberculosis, 

 and other infectious maladies are tiny parasitic organisms that be- 

 long to the marvelous world of microscopic plant life. The practical 

 advantages already foreshadowed by these investigations have at- 

 tracted the attention of biologists throughout the world, and many 

 powerful instruments have now been turned in this direction, to study 

 the life-history of these germs, both in health and disease. Yet long 

 before the contagium vivum had been discovered, pathologists, be- 

 lieving that the morbific principle affecting the system, in a large 

 group of epidemic and sporadic forms of disease, closely resembled 

 the action of a ferment, proposed the zymotic theory, which, though 

 vague in its chemico-physiological significance, has been almost 



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