222 THE POPULAR SCIENCE MONTHLY 



sistant to the action of several drugs, which simplifies such work still 

 further. In thus employing the unstable coal-tar products to destroy 

 organisms made up of labile protoplasm, Ehrlich has opened up an en- 

 tirely new field of therapeutics. As Morgagni, the first pathologist, 

 treated of the seats and causes of disease (De sedibus et causis mor- 

 borum), so Ehrlich has sought (he claims) to gain a fuller knowledge 

 of the distributive and local causal relations of the finest mechanism of 

 drugs, de sedibus et causis pharmacorum. 18 



In deploying this vast chemical knowledge against protozoan disease 

 Ehrlich has been likened to a general who aims to take a fort by in- 

 vesting it on all sides. In the other important respect he resembles 

 a great commander — in the possession of an imagination lively and 

 keen enough to figure out the enemy's possible movements as the first 

 step towards checkmating him. The true fighter always respects his 

 adversary, and Ehrlich, who, in profile, looks so much like Thomas 

 Carlyle, has taught physicians to have a very wholesome respect for 

 their adversary, the disease germ. He has seen and demonstrated that 

 the parasites of disease can protect themselves against man's attacks, 

 that in this respect they are as wary and fertile in resource as we. In 

 the future history of medicine he will have his high place as the most 

 original thinker of his time in regard to the nature of infectious disease, 

 as a leader in synthetic chemistry, and as a foremost champion in hu- 

 manity's "KulturJcampf gegen den Tod." 



18 Ehrlich, Harben Lectures ("Experimental Researches in Specific Thera- 

 peutics"), London, 1908, 88. 



