176 SECTIONAL ADDRESSES. 



Hexyl Resorcinol is represented by the formula C6H3(OH)2C6Hi3. It 

 has a phenol coefficient of 72 and it renders the urine in which it is- 

 excreted germicidal ; many reports show that it effects remarkable cures 

 in cystitis and pyelitis. Unlike me'rcurochrome the action of this 

 substance, at least in the urine, may be direct on micro-organisms. 



Attention has already been drawn to the important part played by 

 surface tension in the destruction of micro-organisms by drugs : those 

 substances in solution which depress surface tension are the more efficient 

 germicides because they penetrate better ; they are adsorbed by particles 

 in suspension like bacteria, and they diffuse through the cell membrane 

 inversely as the surface-tension is lowered. The alkyl derivatives of 

 resorcinol all lower surface-tension, but the hexyl derivative most, and its 

 bactericidal properties are largely dependent on this factor. In all this 

 series of alkyl derivatives of resorcinol the bactericidal power was found 

 to be directly inverse to the surface-tension. Frobisher found that using 

 a wide range of dilutions the bactericidal efficiency could be precisely 

 controlled by manipulating the surface-tension of these solutions by the 

 addition of varying amounts of surface-tension depressants which are 

 themselves devoid of bactericidal action. Thus Leonard has shown that 

 0-1 per cent, hexyl resorcinol with 30 per cent, of glycerine and water 

 to 100 is one of the most powerful germicides known and possesses a 

 surface-tension of 37 dynes per centimetre. Pathological organisms are 

 destroyed by this fluid within 15 seconds. 



The chemo-therapeutic substances which are known to act on bacteria 

 are without value in tuberculosis. Thus flavine and its silver salts do not 

 influence the tuberculous process in living animals, and the same is true 

 of the quinine derivatives which have been prepared so far. The 

 destruction of the tubercle bacillus presents two special difficulties : first 

 in the fatty and protective envelope surrounding the bacillus, and second 

 in the small blood supply to the tuberculous lesion. 



Success, however, has been claimed for several metallic compounds,, 

 and I shall confine my remarks to three of these. It is by no means 

 clear that the results which have been obtained by administering gold 

 salts to tuberculous patients or animals are superior to those given by- 

 copper salts which preceded them. ' Krysolgan ' was introduced by 

 Feldt ; it prevents the growth of the tubercle bacillus in cultures in 

 1 part in 1,000,000. Nevertheless, animal experiments with this sub- 

 stance are not promising, though the clinical results published in Feldt's 

 monograph in 1923 are certainly both helpful and inspiring. 



Another ' gold ' cure is that recently introduced by Moellgaard. It 

 is a double thiosulphate of gold and sodium, Au(S203)2Na3, which, 

 although a well-recognised substance, he calls ' sanocrysin.' Like its 

 predecessors it retards growth of the tubercle bacillus in glycerinated 

 bouillon in such strengths as 1 in 8,000,000, but how serum added to the 

 cultures affects its action I have not discovered. Nevertheless, this is a 

 very important point, since such chemo-therapeutic substances as exert 

 an undoubted action on bacteria invariably act the better in the presence 

 of the tissue fluids. Moellgaard assumes that his gold injections destroy 

 the tubercle bacillus in vivo, and states that doses which are not poisonous 

 to normal animals kill the tuberculous animal by producing a tuberculin 



