Tu be ratio sis . 415 



Parts per 1000. Killed in . 



Carbolic Acid 50:1000 30" (Yersin) 



" " 10:1000 i / " 



Alcohol (absolute) 1000:1000 5' " 



Ether 1000:1000 io' " 



Iodoform- ether 10:1000 5' " 



Mercuric chloride 1:1000 io' " 



Salicylic acid 2.5:1000 6 hrs. " 



Auiliu water Saturated. 



Thymol 3:1000 3 hrs. (Yersin) 



Formalin vapor 60:1000 40 hrs. (Murray) 



Sulphurous Acid( Sid phur 



1 oz. to cubic metre) __ 14 hrs. (Vallin). 



The following agents proved ineffective : Saturated aqueous 

 solution of creosote, or of B-naphthol, of naphthalin, of potassium 

 iodide, of potassium bromide : — bromine water, iodine water 

 (1: 500), iodoform solution or vapor, vapor of oil of turpentine. 



ACCESSORY CAUSES OF TUBERCULOSIS IN ANIMALS. 



While recognizing that in the absence of the tubercle bacillus 

 there can be no tuberculosis yet we must not ignore the fact that 

 many conditions of the animal system and its environment con- 

 tribute largely to the propagation of the disease on the one hand, 

 or to hinder its progress on the other. None of these conditions 

 can call the germ into being de novo, but in its presence, they 

 greatly favor its diffusion or even its malignancy. Like any other 

 seed, this bacillus requires a suitable soil and favorable climate, to 

 bring out its most destructive development. In striking the bal- 

 ance, we have to guard against the error of so many, who would 

 attribute to the germ alone the deadly results and who assume 

 that these should be the same under all conditions, and the oppo- 

 site error no less prevalent, that ascribes the evil to the conditions, 

 and holds that without these the germ would be harmless. 



Hereditary Predisposition. Racial Vulnerability. Before the 

 discovery of the specific bacillus, when as yet tuberculosis was 

 held to result from a constitutional weakness, or cachexia in which 

 deterioration of cells was held to be the main factor, the disease 

 was held to be mainly hereditary, and its every day transmission 

 in the line of descent, and the increasing mortality to extinction 

 of given families were confidently appealed to in support of the 



