EPIDEMIOLOGY OF TUBERCULOSIS KOCH. 



669 



consumption has been marked and often slowly increasing during 

 2,000 years it is not reasonable to suppose that it would decline all at 

 once without any assignable cause. Besides, the decrease of viru- 

 lence would first be manifested by an amelioration in single cases 



Table S. — Mortality from consumption at New York. 



— o— o— o — 6— o 



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which would also more frequently terminate in recovery. But noth- 

 ing of this kind occurs. It is indeed true that in modern times great 

 advances have been made in the treatment of tuberculosis, and that 

 we succeed, through the so-called hygienic-dietetic treatment and 



