APPENDIX 451 



teenth century, and throughout the seventeenth and eighteenth, 

 one can watch the gradual accumulation of therapeutic know- 

 ledge and skill, growing like the growth of a crystal. The 

 eighteenth century closed with the highly significant discovery 

 by Jenner of protective vaccination against small-pox, by means 

 of which it at last became possible to quell one of humanity's 

 most terrible plagues. This was, as it were, a foretaste of the 

 many blessings which the nineteenth century, so fertile in 

 discoveries, was to bring to suffering humanity. First the 

 discovery of the cell by Schwann and Schleiden ; then the pos- 

 sibility of painless operations by the aid of chloroform ; Pasteur's 

 discovery of the minute living things which induce putrefaction 

 and the morbid infection of the body; following on this Lister's 

 antiseptic system for the treatment of wounds ; Koch's discovery 

 of the bacillus of cholera and tuberculosis, and the possibility of 

 obtaining pure cultures of micro-organisms ; Behring's introduc- 

 tion of the anti-diphtheritic serum, and Rontgen's discovery of the 

 marvellous rays which can pass through solid bodies. Truly 

 we have here, in a single century, such a collection of thera- 

 peutic discoveries of prime importance as exceeds those of all 

 like periods put together. Thousands of sick people who 

 would in earlier times have succumbed to their diseases leave 

 the hospitals cured, and still thousands of doctors are hard at 

 work discovering new remedies for stricken man. 



If to the many other specific human characteristics we are 

 yet to add another, surely it must lie in the knowledge of the 

 causes of disease, and in this never-resting search for new 

 methods whereby the sufferings of unnumbered sick ones may 

 be alleviated or entirely extinguished. 



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