368 COLLOIDS IN BIOLOGY AND MEDICINE 



ually decolorized by them as the gold precipitated on the mycelia and 

 stained them black. 



Earlier investigators (CREDE, COHN, BRUNNER, NETTER) ob- 

 served only a moderate inhibition of growth (1 : 2000 to 1 : 6000 in 

 the case of staphylococcus aureus) but no destruction of the germs 

 by colloidal silver. Recent studies of CERNOVODEANU and V. HENRI * 

 on anthrax bacilli, B. coli, staphylococcus pyogenes aureus and albus, 

 B. dysenteria, etc., show a strong bactericidal action of silver 

 hydrosol in test tubes; researches of CHARRIN, V. HENRI and MON- 

 NIER-VINARD * show the same effect in the case of B. pyocyaneus. 

 The size of the particles in a hydrosol is of very great importance, 

 and in fact the finely granular red solutions are much more active 

 than the coarser green ones; the former completely inhibited growth 

 in dilutions of 1 : 50,000 to 1 : 100,000. [JEROME ALEXANDER has 

 produced especially fine dispersion by a new principle. Tr.] 



Similar results were obtained for pneumococci by CHIRIE and 



MONNIER VlNARD.* 



According to G. STODEL,* colloidal mercury in a dilution 1 : 132,000 

 inhibits the development of B. typhi and of staphylococci. 



On account of the results obtained with colloidal silver, 1 as well as 

 because of the lack of irritating effect and of toxicity (it was pos- 

 sible to employ it in large doses subcutaneously and intravenously), 

 the hopes for its therapeutic action were justified. It is remarkable 

 that, instead of extensive especially planned animal experiments, 

 clinical experiments which were at times favorable and at times un- 

 favorable have occupied the stage. The number of times it has 

 been employed clinically compared with animal experiments is com- 

 paratively small, and it was tried on many hopeless cases. 



The judgment of the results depends largely on the experience of 

 the clinician and is much influenced by the subjects; in short, the 

 results hitherto obtained lead to nothing definite. On this account 

 the indications for use are very inadequate. It is from the above- 

 mentioned exhaustive researches of M. ASCOLI and G. IZAR * that an 

 idea of the mechanism of the action of metal hydrosols has been 

 obtained. [HARRY CULVER (Jour. Lab. & Clin. Med., May, 1918) 

 found that the gonococcidal action of colloidal silver (argyrol, pro- 

 targol, silvol and nargol) was diminished in vitro by aging the solu- 

 tion by light and by heat. He also found that the gonococci became 

 resistant or adapted to a particular preparation by growth in its 

 presence. This was not a resistance to the other colloidal silver 

 preparations but specific. The importance of the " protecting " sub- 

 stance is evident from this experiment. Tr.] 



1 According to STODEL also, colloidal mercury is less toxic than mercury salts. 



