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INSECT PORTERS OF BACTERIAL INFECTION. 



LECTURE I. 



MR. PRESIDENT, I would first of all express to you, Sir, 

 and the Censors of the College my appreciation of the 

 honour you have done me in electing me to deliver the 

 Horace Dobell lecture. I feel, however, that it will be 

 impossible for me to do justice to the fine spirit which 

 actuated the founders of the lectureship during their lives' 

 work. 



To successfully interfere in bacterial diseases of man and 

 animals it is most important to know accurately the life- 

 history of the parasite outside the host how it leaves the 

 old host, how it enters a new host, and where and how it 

 passes the intervening period. If we are in possession of 

 these facts our efforts in the struggle can at any rate be 

 intelligently directed and concentrated against the most 

 vulnerable point of the enemy. The exercise of an adverse 

 influence upon bacteria, once they have gained a footing in 

 the body, has hitherto not been generally successful, although 

 recent developments in chemotherapy have shown that there 

 is ground for optimism in this direction also. 



In the early days of bacteriology, before the large number 

 of pathogenic bacteria had been discovered and their pecu- 

 liarities had been studied, it was generally assumed that 

 bacteria once let loose from the body survived long periods 

 upon inanimate objects and in water, soil, &c. ; and efforts at 

 prevention were directed to an indiscriminate disinfection of 

 the belongings and surroundings of the patient. Some bacteria 

 do, indeed, possess considerable powers of survival under such 

 circumstances, and I would not be understood to deprecate 

 measures of general disinfection. The majority of patho- 

 genic organisms, however, are fortunately delicate creatures, 

 and rapidly succumb to such adverse influences as drying and 

 sunlight. 



Another factor which must not be lost sight of is that 

 many organisms which have acquired by selection the pro- 

 perty of withstanding the adverse influence obtaining in the 



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