1022] The Search for Specific Remedies 635 



WEEKLY EVENING MEETING, 

 Friday, May 12, 1922. 



John Mitchell Bruce, Esq., C.Y.O. M.A. M.D. LL.D. F.R.C.P., 

 Manager and Vice-President, in the Chair. 



H. H. Dale, C.B.E. M.D. F.R.S., Head of Department of 

 Biochemistry and Pharmacology under Medical Research Council. 



The Search for Specific Remedies. 

 [Abstract.] 



The idea of discovering for each disease a specific remedy is not a 

 new one, and some of those discovered in the pre-scientific period 

 are still the best available for certain infections. The study of 

 immunity, and of the remedies produced by the natural reaction of 

 the body, for a time diverted interest from the artificial medicines in 

 which mankind had formerly trusted, and brought them into discredit. 

 When the limitations of immunological therapeutics began to appear, 

 •the search for artificial remedies, for infections to which little natural 

 immunity is developed, began on new lines and with new aims, which 

 the study of Nature's methods had indicated. The search now to be 

 undertaken, with the newly gained resources of synthetic chemistry, 

 was for substances which should resemble the natural antibodies in 

 being specifically harmful for the parasite and harmless for the patient 

 — in Ehrlich's phraseology, maximally parasitotropic and minimally 

 organotropic. 



The problem might well have appeared hopeless. AVhat little is 

 known of the chemistry of the infective micro-organisms suggests that 

 it is very similar to that of our own body cells, and the problem was 

 to find a chemical substance adapted to combine with the one and not 

 with the other. 



Ehrlich started his search by investigating a number of synthetic 

 dyes, his use of which as microchemical reagents has shown their 

 differential affinities for different types of cell. He had at disposal 

 the technique of transmitting infections with trypanosomes developed 

 by Laveran and Mesnil. A dye of the benzidine series was found 

 which cured mice infected with the trypanosome of "Mai de Caderas, 1 ' 

 and to this the name ;i trypan-red " was given. It had little curative 

 action, however, on infections with the trypanosomes of other diseases, 

 or on the infection of other species with that of " Mai de Caderas." 

 Nor were the trypanosomes of " Mai de Caderas " obviously injured 



