CONTAGIOUS DISEASES. 259 



Evening Session. 

 The evening session was held in the Opera House, where 

 a lecture was delivered by Surgeon-General Alfred F. 

 Holt of Cambridge, on Contagious Diseases in our Homes, 

 and how to prevent them. The lecture was illustrated with 

 stereopticon pictures, and was attentively listened to by a 

 large audience. 



CONTAGIOUS DISEASES: 



HOW THEY ARE CAUSED AND HOW TO PREVENT THEM IN 

 OUR HOMES. 



During the long history of medicine, reaching far back 

 into the older civilization, there have been many theories 

 entertained by the medical profession as to the cause or 

 causes of disease ; but all of these theories, except the one 

 generally accepted by the scientific world to-day, have been 

 purely speculative and theoretical. Some of these were 

 evolved by a subtle reasoning from false premises, some 

 from an ignorance of physiological laws, while still others 

 were based wholly upon a blind and ignorant superstition. 



Each of these medical theories has had its day. Each, 

 for a time, has been bolstered up and sustained, as all false 

 hypotheses have been, by the addition of new propositions 

 and new guesses, until it has fallen by its own weight, or 

 perhaps has been dispelled by an advance in knowledge ; 

 when another, possibly equally as absurd and false as its 

 predecessor, has arisen to take its turn. But all of these 

 speculative theories as to the cause of disease are matters 

 of history, and to-day they only serve to show us the 

 methods of reasoning of our predecessors and the darkness 

 and ignorance in which they were groping. 



The present theory of the cause of the diseases with 

 which sanitary science has to deal, — the so-called conta- 

 gious or preventable diseases, — and the one almost univer- 

 sally accepted by the medical profession, rests upon no such 

 insecure basis as a speculative supposition, but has for its 

 foundation the firm, strong groundwork of careful and 

 extended experimental research. In fact, it is rather an in- 

 evitable conclusion, that has been forced upon us by the 



