LADY MONTAGU AND MODERN BACTERIOLOGY. 371 



Still, he had the satisfaction of seeing compulsory vaccination 

 established in many of the countries of Europe, and knew that it 

 was making its way among enlightened peoples everywhere, be- 

 fore his death in 1823, which occurred in his native rural home, 

 where he had returned after a short and distasteful residence in 

 London. Ten days before his death he got a letter, on the back 

 of which he wrote the following : " My opinion of vaccination is 

 precisely as it was when I first promulgated the discovery. It is 

 not in the least strengthened by any event that has happened, for 

 it could gain no strength. It is not in the least weakened, for if 

 the failures you speak of had not happened, the truth of my as- 

 sertions respecting the coincidences which occasioned them could 

 not have been made out." 



In the seventy years since, evidence has accumulated as to the 

 inestimable value of the original discovery; wide observations 

 among thoroughly trained medical men have also demonstrated 

 the value of revaccination after maturity of persons who had 

 been vaccinated in infancy ; but the most glorious result of all 

 was to be the illumination of Pasteur's great scientific mind, as to 

 the possibility of the production of a modified virus in other dis- 

 eases than smallpox. 



Modern science contains no more interesting chapter than the 

 one which shows how that, after the achromatic compound micro- 

 scope magnifying close on to two thousand diameters was put 

 into the hands of scientists, step by step it was shown that what 

 we call zymotic or "catching" diseases are caused by the living 

 germs of parasitic plants entering the blood, and there multiply- 

 ing and growing, deriving the needed sustenance from the blood 

 itself. Pasteur caught the idea of a modified growth from Jen- 

 ner's experiments, as he distinctly said in his original paper on 

 anthrax, read before the French Academy. That it is within the 

 power of man' to modify plants outside the body, any one who has 

 tasted a native astringent crab and a delicious Baldwin apple will 

 believe, but it remained for a devotee of science for its own sake 

 like Pasteur to observe and experiment and think till he achieved 

 that " attenuated virus " which annually saves millions of animals 

 in Europe from the ravages of anthrax, and multitudes of men 

 from death by hydrophobia through the bites of wolves, dogs, and 

 cats. The statistics of the Pasteur Institute of Paris show that in 

 the five years from January 1, 1886, no less than nine thousand 

 four hundred and thirty-three persons were treated, of whom 

 fifty-eight died, or 0'61 per cent. The instrument of this merciful 

 exemption was a modified i. e., attenuated virus. 



With such results, such victories of the wit of man over Na- 

 ture, while bacteriology is yet in its early infancy, it is no won- 

 der that Pasteur predicts the time when "these diseases will be 



