CHEMICAL REMEDIES 293 



would one day be treated practically by the same remedies. 

 Yet analogies were already in existence to act as a guiding 

 principle, for the name of horse-syphilis had long been given 

 to a trypanosome disease, dourine, which possesses clinical 

 resemblances. It was Schaudinn, again, who maintained 

 from his study of the facts the relationship between trypano- 

 somes and spirochaetes ; he was convinced that a protozoon 

 cannot be properly known until its biological cycle has been 

 followed completely, and he therefore studied the haematozoa 

 as a zoologist and found in the development of the same 

 species trypanosome forms and spirochaetes. When the 

 spirochaete of syphilis came under his eye, he was not only 

 prepared to see it but to believe it and maintain it. There 

 was great discussion in the scientific world as to the relation- 

 ships of this new microbe : was it a protozoon or a bacterium ? 

 These researches had the happy result of drawing attention to a 

 problem which concerns medical practice much more closely 

 than was guessed, and they prepared the way for the revolution 

 in the treatment of syphilis. 



This sprang from an old idea. In an article dated 1867 in 

 the Dictionnaire des Sciences medicales^ one may read that arsenic 

 occasionally succeeds in completing a cure after mercury and 

 iodine : " it is especially the symptoms which have resisted the 

 former treatment which yield to the action of arsenic." 



The arsenical treatment of syphilis is an adaptation of the 

 arsenical treatment of the trypanosome infections, inspired by 

 the ideas of Schaudinn and the labours of Ehrlich. 



Salmon was the first to undertake in Metchnikoffs laboratory 

 methodical studies with atoxyl. The well-known toxicity of this 

 substance confined him to small doses. Arsenophenylglycine, 

 employed by Alt in general paralysis, was found to produce 

 temporary improvements. It was in December, 1909, that 

 Ehrlich mentioned for the first time a new substance con- 

 taining the same arsenobenzol group as arsenophenylglycine, 

 namely, the dioxydiamidoarsenobenzol, famous to-day under 

 the name of " 606 " or Salvarsan. 



All that has been published hitherto on Ehrlich's remedy con- 



