10 The Philippine Journal of Science i9i> 



dicidal action of silver nitrate show it to be an equally efficient 

 balantidicide as the more poisonous mercurial salts. It does 

 not act quite so quickly at the dilution of 1 part in 20,000, but 

 its balantidicidal activity extends to slightly higher dilutions, 

 a part of the balantidia being killed at the dilution of 1 part 

 in 25,000. 



The salts of mercury and silver are, therefore, much more 

 balantidicidal than any of the other drugs or chemicals that 

 have been tested; but their application to the treatment of 

 balantidiasis is subject to certain limitations. The salts of 

 mercury and silver nitrate are precipitated on coming in con- 

 tact with albumin, and the albumin is coagulated, forming an 

 impervious layer. Therefore, when employed for local treat- 

 ment they are quickly rendered inert and possess little power 

 of penetrating the tissues. 



A search was, therefore, instituted for some compound of 

 these metals which possess to some degree the eminent balan- 

 tidicidal activity, which are not precipitated by albumin, 

 and which might at the same time be less toxic than the 

 ordinary inorganic salts. Substances satisfying these require- 

 ments to a greater or lesser degree appear to exist in the organic 

 compounds of silver. Some 15 or 20 of these compounds of 

 silver are known. They are said not to be precipitated by 

 albumin or, if precipitated, to form compounds soluble in an 

 excess of albumin. And it is claimed for many of them that 

 they are as strongly germicidal as, and much less toxic for man 

 than, the nitrate of silver. Accordingly, as many of the more 

 promising of them as could be obtained have been tested for 

 their balantidicidal value. The name, composition, percentage 

 of metallic silver, and notes on the toxicity for mammals of 

 the compounds, and the results of the tests of their balan- 

 tidicidal action are given in Table II. Corresponding data of 

 silver nitrate are included for comparison. 



It is evident from this table that these organic compounds 

 of silver are extremely variable in their balantidicidal action. 

 In general, the larger the percentage of metallic silver, the more 

 actively balantidicidal is the compound. But this does not in- 

 variably hold good; for argyrol, which contains about one-third 

 as much silver, is only one two-hundredth as balantidicidal as 

 silver nitrate. It is probable that a number of factors influence 

 the balantidicidal action of these compounds. Of these, the 

 silver content is perhaps the chief; but the action on albumin 



