1 ' President's Address 



that it consisted, not only of dust, but of debris of animal 

 tissues, and, most important of all, of germs of living 

 organisms. He pointed out the high probability that the 

 inhalation of these organic impurities was the cause of much 

 disease, and he adduced many startling instances of the rapid 

 spread of parasitic organisms in wounds and delicate surfaces 

 of the human frame which had been unduly exposed to these 

 impurities of the air. 



Preceding and contemporaneous with Professor Tyndall's 

 researches in this du-ection, we find many well-known and 

 able men engaged in work and discussion of what is known 

 as " The Germ Theory," which may be briefly defined as a 

 question " whether living things of a necessity spring from 

 living things or no ? " Results of numbeiless experiments 

 and patient research have been advanced for both sides of 

 the question by Darwin, Huxley, Bastian, Frankland, 

 Calvert, and others ; but I believe it will be admitted that 

 the evidence against the spontaneous generation theory, and 

 in favour of the necessary pre-existing germ, is at the present 

 moment by far the strongest, and getting stronger. \ 



But the portion of the germ question I wish to draw your 

 attention to more especially is that which affects us more 

 directly — the question whether germs which can float, and 

 be wafted in the air, are capable of planting themselves in 

 our bodies, and there give rise to disease. Professor Tyndall, 

 in the lecture above referred to, pointed out how readily these 

 organisms could be filtered from the air we breathe by respiring 

 through a handkerchief or through cotton wool, and the value 

 of such a precaution in malarious and disease-stricken localities. 



And several travellers have since certified to the value of 

 sleeping under muslin or fine mosquito tents in the fever 

 districts of Africa and India, and the immunity from fever 

 enjoyed by those adopting this precaution. Professor Tyndall 

 again lectured on this subject in June last, and gave some 



