99 



gradually weaker, until at last it was so reduced that jDrotec- 

 tiou to dogs was afforded by inoculation. 



Our time will not permit me to proceed further. I have but 

 glanced at the subject under notice, but 1 hope sufficient has 

 been brought out to show that we are on the threshold of a 

 vast inquiry. In pursuing it we shall make many mistakes, 

 but the light will come, and even our mistakes will serve as 

 beacons against future errors. All real progress is slow. It 

 was not till 200 years after an English writer described 

 the parasite of that loathsome disease, the itch, that the 

 ^yidence was accepted; and yet this affection is external, and 

 the parasite is large enough to be seen with the naked eye. 

 'Now and then the discovery of the parasite was reported, but 

 few believed it, and down to our own time little or nothing 

 was known of its nature. We find some of the older writers 

 stating that the disease was caused by a chemical sort of phlegm, 

 by a peculiar ferment in the blood, by a bilious humour 

 of the body, by deranged secretions, and so on without end. 

 I could find 3^on books of recent date where the same rigmarole 

 is still indulged in to account for typhoid and other fevers. At 

 the close of last century Lorry denied that anyone had ever 

 seen the parasite of scabies or its eggs, and contended that the 

 parasitic theory could not be true — (I) Because some acute 

 diseases had been cured as soon as the itch broke out ; (2) 

 because it was known that the itch was driven in to external 

 organs ; (3) because many serious diseases could be cured by the 

 inoculation of itch. Change the name of the disease and I 

 wdll find you modern parallels equally conclusive. As late as 

 1833 Cazenave wrote that as to the immediate cause of scabies 

 *'it is still entirely unknown. Some have attributed it to the 

 presence of an insect, but we believe ourselves authorized to 

 think that the acarus scabiei has no existence." "Within a year 

 of that time there was not a clinic in Europe where the acarus 

 had not been exhibited. If then it required 200 years to com- 

 plete an inquiry of this kind nnder the most favourable condi- 

 tions, need we be discoura<:jed if under conditions infinitel}' more 

 difiicult to control, we find our progress slow, or if now and 

 again we have to retrace our steps through straviuginto wrong 

 paths. Remember that we have a grand object before us, the 

 stamping out of all infectious diseases. Some of us cannot 

 hope to live long enough to see this consummation, but we are 

 encouraged to believe that younger men will take up the work 

 w^hich older and, it may be, feebler hands have begun ; and 

 w^hen I look round this Society, and on its younger offspriu]^ 

 — the Field Naturalists' Section — and when t witness that we 

 have amongst us gentlemen who already are showing interest 

 in microscopical and biological research, am I anticij)ating too 



