AND PREVENTION OF PHTHISIS. 413 



comes into contact, and conflict, with the living cells 

 underneath. It is not any such predisposition, but pre- 

 disposition by inheritance as a source of phthisis that is 

 contended against by Cornet. That Koch entertained a 

 different opinion is declared to be absolutely erroneous. 

 The admission that a disease may be favoured, or pro- 

 moted, by this or that circumstance is not tantamount 

 to the assertion that in all, or nearly all cases, this cir- 

 cumstance is the cause, concomitant, or necessary pre- 

 cursor of the disease. This is the view generally enter- 

 tained regarding " predisposition." 



Cornet's further reasoning on this subject reveals 

 his views so clearly that I will endeavour, in substance, 

 to reproduce it here. Let a box be imagined filled with 

 finely-divided bacillus dust, and let a certain number 

 of guinea-pigs be caused, for a very short time, to inhale 

 this dust. A few of them will be infected, while the 

 great majority will escape. If the inhalation be pro- 

 longed, the number of animals infected will increase, 

 until at length only one or two remain. With an ex- 

 posure still more prolonged the surviving ones would 

 undoubtedly succumb. Why, then, in the first instance, 

 does one animal contract tuberculosis and another not? 

 Have they not all inhaled the same air, under the same 

 conditions? Are the animals that have escaped the 

 first contagion less " disposed " than the survivors to the 

 disease? Assuming the animals to be all perfectly 

 healthy, such differences will be observed. But, sup- 

 posing them to be weakened in different degrees by pre- 

 vious disorders, the differences revealed in the case of 

 healthy animals would be more pronounced. This, with 

 human beings, is the normal state of things. 



Take the case of a veteran who has been to the 

 front in fifty different battles, who, right and left of 

 him, has seen his comrades fall, until haply he remains 



