272 "SPECIFIC TREATMENT" OF DISEASE 



that it had a remarkable effect on the trypanosomes 

 which cause this group of diseases. When injected 

 into animals harbouring millions of trypanosomes 

 in their blood, it was found that the parasites 

 quickly disappeared and the animals showed rapid 

 recovery. The recovery was, however, brief, for 

 after a while the trypanosomes reappeared and it 

 was found that with time they had grown resistant 

 to the dye. These results gave promise and sup- 

 ported the view advanced by Ehrlich that by 

 logically conducted research specific remedies might 

 be found for the various specific diseases. He 

 tested a vast array of substances and found a few 

 which exerted an appreciable effect, and by un- 

 remitting toil scored some brilliant successes to 

 which we shall presently refer. 



Meanwhile, in France, another dye to which 

 Mesnil gave the name of trypan-blue had been found 

 to have an advantage over trypan-red in that it 

 produced much less injurious local effects when 

 injected into experimental animals suffering from 

 trypanosomiasis. It was found, however, not to 

 effect a permanent cure, and was abandoned in 

 favour of the better treatment subsequently dis- 

 covered by Ehrlich. 



Trypan-blue was found by Nuttall and Hadwen 

 to be a very useful remedy for another group 

 of protozoal diseases. In cattle, horses, sheep 

 and dogs there occur affections which may be 

 broadly compared to malaria in man, since the 



