D. B. WARD, M. D. 85 



SO the diatoraists or, as some call them, the diatom aniacs, 

 called on the optician for better glasses, and men of 

 science and brains worked on new mathematical formulae 

 and chemists tried experiments to obtain glass of higher 

 refractive power, and the water immersion lens was in- 

 vented and the lines were faintly seen. 



After that the oil immersion or homogeneous immer- 

 sion objective, where the ray of light goes through a 

 homogeneous medium from the bottom of the condenser 

 to the front of the objective, and then followed later the 

 splendid apochromatics of Zeiss, the nearest approach to 

 theoretical perfection at present obtainable. The exist- 

 ence of these magnificent instruments has made possible 

 the newest of the sciences — bacteriology — and has been 

 the means of adding the wonderful discoveries of Pasteur, 

 Koch and Lister to the sum of human knowledge, What 

 these mean is not perhaps fully appreciated outside the 

 medical profession. Twelve years ago Koch discovered 

 the bacillus tuberculosis, but consumption is still incura- 

 ble (practically). Ten years ago he discovered the comma 

 spirillum of cholera, and cholera still destroys half its 

 victims, but we battle now with a known enemy and no 

 longer fight in the dark. I have no doubt that the 

 close of the next century will see the last of the bacillus 

 tuberculosis and its victims, who now number one- 

 seventh of the human race, and this will be accomplished 

 by sanitary means alone and not by the discovery of 

 any specific cure for the disease. 



But in surgery— thanks to Lister— the gain is immedi- 

 ate and immense. Operations are done now without a 

 thought of evil results which would have been regarded 

 as assault with intent to kill when I was a medical stu- 

 dent eighteen years ago. 



Now for all this, and this new science is only in its 

 infancy, the humble diatom is largely responsible, and 

 this is perhaps Us chief claim to the respect of humanity. 



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