CHAPTER XVIT. 



ON RELATIONS OF SEPTIC TO PATHOGENIC ORGANISMS. 1 



THERE is hardly any question which to the pathologist and 

 sanitary officer can be of greater importance than the relation 

 of septic to pathogenic organisms. To the pathologist the life 

 history of a micro-organism, outside and within the animal 

 body, must ever remain an important field of inquiry ; to the 

 sanitary officer all conditions affecting the life and death of 

 those organisms which produce, or at least are intimately bound 

 up with, infectious diseases, such as the distribution and growth 

 of these micro-organisms outside the animal body, the agencies 

 which affect it in a favourable and unfavourable sense, are the 

 points which he has particularly to consider in dealing with 

 the spread and prevention of infectious maladies. Now, it is 

 known of many micro-organisms, both those that are associated 

 with putrefactive processes as well as those that are bound up 

 with infectious disease, that temperature, the medium in which 

 they grow, presence and absence of certain chemical compounds 

 are capable of materially affecting them. I need not for this 

 purpose enumerate all that is known already by direct experi- 

 ment, but will only limit myself to reference to the researches 

 of Schroter, Colin, and Wernich on that group of micro-or- 

 ganisms known as pigment bacteria, i.e. bacteria which only 

 under certain conditions, notably temperature and soil, produce 

 definite pigments (Cohn's Beitrage zur Biologie d. PJianzen) ; 

 to those of Hansen (Carlsberg Laboratory) on yeast ; to those 

 of Neelsen on the bacilli producing the "blue colour of milk, 

 the bacillus syncyanus (Beitr. zur B'wl. d. Pflanzen, iii. 2, 

 p. 187) ; to the works of Toussaint, Pasteur, Chauveau, Koch, 



1 The greater part of this chapter is copied from an interim report by myself 

 to the Medical Officer of the Local Government Board, 1884. 



