Recent Developments in Public Hygiene. xxv 



air of streets. It appears, therefore, that sewage matters 

 provide a good breeding ground for that particular class of 

 micro-organisms, to which the infecting agent of typhoid 

 belongs. Evidence of an exact and positive kind is there- 

 fore accumulating in favour of the view which, in my 

 opinion, hardly admits of doubt that — defective drainage is 

 the real cause of the great prevalence of typhoid in 

 Melbourne. In that, and in our bad system of nightsoil 

 disposal, we have insanitary conditions fullj^ adequate to 

 account for the great and continued prevalence of the 

 disease, and I can see no hope of such inijDrovement as 

 has come about in the English towns, till we adopt their 

 sanitary methods. It is vain to put our trust in disin- 

 fectants. The cure consists in the adoption of a system 

 of drainage, whereby all household slops, all liquid refuse, 

 and nightsoil with it, are swept away at once from the 

 neighbourhood of our houses. If that were done, our 

 scavenging would also be comparatively an easy problem. 

 An underground system of drainage can and must be 

 carried out, and in the saving of life and health there 

 would be ample repayment of the cost. 



There are certain diseases of animals which human beings 

 may acquire. In addition to various forms of parasites, 

 mention need only be made of anthrax, glanders, hydro- 

 phobia, and the familiar cow-pox, which, by the method of 

 vaccination, has come to be looked on rather as a preventive 

 than as in itself a disease ; but in all these cases, the spread 

 from animal to man is either a comparatively rare accident, 

 or at least, as in the case of vaccination, has to be 

 deliberately produced. It can hardly be said, indeed, that 

 we are acquainted with any disease of this general class, 

 which spreads freely from animals to human beings by 

 what may be called ordinary methods of contagion. In 

 the same way, none of the general zymotic diseases which 

 affect human beings, spread easily to the lower animals if 

 the latter, indeed, are susceptible of contagion at all. This 

 circumstance has made, and will make, it difficult to obtain 



