ANNIVERSARY ADDRESS. 25 



We have yet the important question to consider — What likeli- 

 hood is there of there being disease-producing organisms in the 

 sewers 1 There can be no doubt that such organisms do reach 

 the sewers by the dejecta, etc., of persons and animals, especially 

 during epidemics. But, even then, the numbers of the harmless 

 microbes are immensely greater than the numbers of the harmful; 

 and we have no reason to suppose that the harmful organisms 

 rise into the sewer air more easily than the harmless. Thus 

 even in epidemics, the proportion of harmful microbes in the sewer 

 air would be small. But all who have tried to make pure cultures 

 of pathogenic organisms, have found how difficult it is to satisfy 

 all the necessary conditions as to temperature and medium, and 

 can understand how unlikely it is that the sewage will offer 

 favourable conditions for their growth and multiplication. Lastly, 

 they will have to compete in the struggle for existence, for food, 

 with the vast numbers of the harmless sorts. Altogether it does 

 not seem likely that the pathogenic organisms will readily thrive, 

 or even survive, in their new surroundings in the sewage. 



Finally, let us assume that the sewer air really does contain 

 disease-producing organisms, and actually reaches the outer air. 

 They are here in a usually much drier medium than while still in 

 the sewer, and many are killed by the mere drying. They are also 

 exposed to sunlight, and this alone kills many more. Lastly, 

 the survivors are distributed through so large a quantity of air 

 that the chances are more and more against any one ingesting 

 them in such numbers that they overcome the body's protectors, 

 as already described, and really produce their specific disease. 



SANITARY LEGISLATION IN NEW SOUTH WALES. 



A review of the Acts in force in New South Wales relating to 

 the public health unfortunately does not take long. They are as 

 follows, viz. : — 

 The Quarantine Act and its Amendments, 1832 - 53. 



These Acts deal only with maritime quarantine and the segregation of 

 introduced disease. They do not even apply equally fully to all the ports 

 of the Colony. 



