lo Aug., 1913.] The Etiology of Contagious Diseases. 



501 



FIG. 2 



ni.sed only when the disease is well 

 advanced, and most are familiar with 

 the wasting, cough, &c., produced 

 (Fig. 32). A verv common method 

 of spreading is per medium of a 



LUNGS AND LIVER OF A 



COW' AFFECTED BY TUBERCULOSIS. 



FIG. J9. BACILLUS OF TUBERCULOSIS. 



milk supply (Figs. t^t^. 34). A cow may be dangerousK tubercular, 

 yet continue to look and act like a healthy animal ; she may show 

 neither symptoms of disease nor discomfort ; her appetite may be 



Fu.. jo. cuw a)'I'.\i-;i:m !,\ iiiAiim, sikoxg and vigorous, giving a 



LARGE QUANTITY OF MILK. KNOWN TO BE AFFECTED WITH TUBERCULOSIS 

 FOUR YEARS. 



good ; she may conceive and milk like an ordinary cow, and mav 

 even be the sleekest and fattest in the herd. The illustrations shown 

 are those of cows apparentlv in the best of health ; some of them. 



