324 DE NOVO ORIGIN OF BACTERIA 



low vitality and bad hygienic conditions may have sufficed to 

 produce it. But, it will be said, you forget the presence of the 

 tubercle Bacillus. To which I would reply. Have not the 

 experiments made for the artificial production of " Pasteur's 

 septicaemia " almost completely got over this difficulty ? The 

 injection of a small quantity of a germ-free chemical irritant into 

 the subcutaneous tissue of a healthy rabbit has made it plain that 

 pathogenic microorganisms may either be produced by hetero- 

 genesis in the focus of inflammation thus caused, or else that 

 the germs of common Bacilli existing in the healthy animal on 

 which the experiment has been made have been roused, rendered 

 extremely virulent, and have been converted, in fact, into 

 pathogenic BaciUi, henceforth capable of acting as contagia for 

 the indefinite propagation of this form of septicasmia. Here we 

 have had, over and over again, in the plainest way, the de novo 

 production of a contagious disease in which, as in phthisis, Bacilli 

 act as the contagia. Why, then, should not an analogous process 

 be similarly possible in the case of phthisis and other tuberculous 

 affections ? A Bacillus just as specific in its characters as the 

 Bacillus tuberculosis makes its appearance also when " Davaine's 

 septicaemia" is produced experimentally.' 



Half a century ago, and less, many conditions now termed 

 " tuberculous " were then spoken of as scrofulous ; and scrofula 

 was recognised as a condition of low vitality in which inflamma- 

 tions of skin and mucous membranes were common, in association 

 with enlargements of lymphatic glands in the neck and axillae, and 



' In a recent Address delivered by Prof. Adami of Montreal (" British Medical 

 Journal," May 27, 190S, p. 1135), he cites a very distinct case in which certain 

 common Bacteria under the influence of altered conditions of life have had their 

 metabolic processes completely altered so that, as he says, " From having been 

 perfectly harmless they are now pathogenic and can set up disease." He then 

 makes the following remarks : " What is to be said concerning the tubercle 

 bacillus in this connection ? In the first place we may have the complete 

 assurance that Adam was not created suffering from tuberculosis. The bacillus 

 we may be fairly sure, from living it may be on food-stuffs outside the body, 

 accustomed itself first to living on the surface and in the passages of the organism 

 as a harmless saprophyte, and only later gained the power of living not on but in 

 the tissues, and from that moment it became pathogenic." He goes on to say 

 that this "must have happened centuries and centuries ago," seeing that the 

 disease was well known to early Greek writers on medicine. But all that we 

 know of Bacteria would lead us to believe that days, or at most a week or two, 

 would suffice for the passage from the non-pathogenic to the pathogenic mode 

 of life ; and what took place in the days of the early Greeks, and before their 

 time, may be taking place now. 



