AND MEDICAL SCIENCE 327 



blood. He discredits the now commonly accepted views as to the 

 frequency of infection through the lungs. It seems true that he 

 has proved the possibility of infection with tubercle or other Bacilli 

 in the manner he indicates. I, on the other hand, have proved the 

 possibility of their de novo origin. He postulates long periods of 

 latency after systemic infection, hard to be believed ; and ulti- 

 mately requires agencies for waking the tubercle Bacilli into 

 activity, just such as I suppose may be adequate for calling them 

 into being — namely, malnutrition and conditions of lowered vitality, 

 howsoever produced, though among such factors impure air and 

 inadequate or improper food must take an important place. 



It would, of course, be an easy step to recognise the extreme 

 probability that the conditions which had sufficed for the appear- 

 ance of the characteristic Bacilli in the glands and in the joints 

 might also obtain in the lungs. We might then return to something 

 more like the sober views that prevailed concerning the etiology of 

 phthisis only a few years ago, when the affection was freely recog- 

 nised as generable in the individual, altogether apart from contagion, 

 and contagion was supposed to take only a limited share in the 

 production of the disease. This seems the more rational and most 

 warranted view to take. It is one which would tend to lay stress 

 upon the need for prevention as well as cure, but it would not 

 encourage the view that the disease could be exterminated, or even 

 very largely diminished, by the provision of " sanatoriums" and by 

 efforts to minimise the risk of contagion. I merely mean to imply 

 that, in my opinion, contagion is as much over-rated as genesis is 

 under-rated, and that our notions concerning prevention must not 

 be too much centred upon the mere elimination of contagion. 



I will only briefly refer to one more disease, but to one having 

 several points of agreement with the affections last considered and 

 concerning which much discussion has been taking place of late. 

 I allude to that terrible affection Leprosy, which is generally admitted 

 to be contagious only in a low degree, and under the influence of 

 very special conditions. Being an affection so slightly contagious 

 and yet so widespread in different countries, the question naturally 

 arises, Is it not also generable de novo ? It was in the past freely 

 believed to be so, but since 1874, when Henson discovered that a 

 Bacillus was always to be found in the tissues affected, there has 

 been a growing antagonism to this view, owing to the yearly 

 increasing importance of bacteriological work and to the ultra- 



