CHEMICAL REMEDIES 289 



valuable method for anatomical analysis as follows : the 

 animal is injected with methylene-blue and is then killed, and 

 one finds in sections the nerve-fibres as fine blue Unes. By 

 injecting the same dye into a frog, the nervous system of the 

 parasites of its body-cavity can be stained in the most delicate 

 way. There are in cells, granules which are stained electively 

 by neutral-red, others by pyrrol-blue. One colour is taken up 

 by the nerve-cell, another by the fatty material, and these 

 stains are more or less specific. Drug treatment ought to be 

 imagined in the same way. To cure syphilis, it is necessary to 

 find a chemical compound which will "stain" electively the 

 parasite of Schaudinn without staining the cells. 



It is curious that we find here again this analogy of staining, 

 so often brought forward by both Ehrlich and Bordet, but with 

 different significations. It is still too soon to ask which is true, 

 the chemical or the physical theory. 



The great merit of a theory is its usefulness, and Ehrlich's 

 theory has certainly stimulated much work. It is not necessary 

 to retain all the scaffolding once the house is built. 



The new impulse of chemiotherapy is scarcely six years old. 

 Research has followed different tracks and attached itself to 

 different chemical substances : hence there arose several 

 methods in which various remedies were soon combined and 

 alternated. 



Here is a list of the principal remedies tried against the 

 protozoal diseases. 



1. Trypan-red and the benzidine colours. 



2. The Triphenylmethane series : malachite-green, brilliant- 

 green, crystal- violet, victoria-blue, parafuchsin, tryparosane. . . . 



3. Antimony, tartar emetic, etc. In historical and logical 

 order this series was studied after arsenic and atoxyl, the 

 chemical relationship of antimony and arsenic suggesting this 

 trial. Tartar emetic acts on the parasite of sleeping sickness : 

 it has been employed in man. Salmon has observed that it 

 ^cts — slightly — in syphilis. 



4. The arsenical bodies and atoxyl. Arsenic is one of the 

 most ancietit remedies. Even before Dioscorides and Pliny, 



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