60 SECTIONAL ADDRESSES 



shaken thoroughly, and the bacteria left alive after 5 and 15 minutes were 

 then estimated, with the following results : 



Tube Solution added 



1. 5 c.c. water 



2. 5 c.c. I : 10,000 amyl-w-cresol 



3. 5 c.c. I : 20,000 „ „ „ 



4. 5 c.c. I : 30,000 „ „ „ 



It was therefore suitable for use as an antiseptic in the oral cavity, 

 and has been successfully introduced into medicine for this purpose. 



Clinical trials of 4-n-amyl-w-cresol as a urinary antiseptic, however, 

 gave disappointing results, but this is true of phenolic bactericides 

 generally. 



Fortunately, a new treatment of urinary infections was introduced by 

 M. L. Rosenheim (1935) two years ago, which is giving excellent results. 

 Previously, urinary infections had been treated successfully by giving 

 patients a particular diet, known as the ketogenic diet, which was very 

 unpleasant to take. It was also known that the principal factor inhibiting 

 the growth of bacteria in the urine of patients receiving this diet was 

 j8-hydroxybutyric acid. This acid, however, if given orally would not 

 be effective, because it would be oxidised in the body. Rosenheim, 

 therefore, studied the bactericidal properties of a number of hydroxy-acids 

 and found in mandelic acid a substance which was not oxidised in the 

 body, was non-toxic in therapeutic doses, and was excreted unaltered in 

 the urine, where it exerted its bactericidal effect, the degree of this 

 increasing with increased acidity of the urine. 



Specific treatment of streptococcal infections has made much progress 

 since the discovery of the properties of particular aromatic sulphonamides 

 by the I.G. Farbenindustrie A.G., and we are lookijig forward to an 

 account of investigations in this field from Prof. Dr. H. Horlein, whom 

 we are very glad to welcome here to-day. 



Amcebicides. 



Research on amcebicides was greatly facilitated by the technique 

 developed by Dobell and Laidlaw (1926), and Laidlaw, Dobell and Bishop 

 (1928) for testing amcebicides in vitro. Emetine (I) has for long been 

 the principal drug used in the treatment of amoebic dysentery, but it has 

 some undesirable by-effects, amongst others a nauseating effect. In a 

 search for substances having the amoebicidal action of emetine without 

 its nauseating effect, a number of alkaloids very closely related to emetine 

 in chemical structure were made at an earlier period. When tested by 

 Dale and Dobell (1917), by an early laboratory method several of them, 

 0-methylpsychotrine (a substance which differs from emetine structurally 

 only in containing two hydrogen atoms fewer) and iV-methylemetine, 

 for instance, were found to be more toxic to Entamoeba histolytica than 

 emetine itself. Clinical trials of O-methylpsychotrine (Jepps and 

 Meakins, 19 17) and A^-methylemetine, however (Low, 1915 ; Wenyon 



