VIII, B. 1 Walker: Balantidicidal Activity 9 



The second surprising result is the feeble balantidicidal 

 action of ipecac and its alkaloid, emetine, which are used so 

 successfully in the treatment of entamoebic dysentery. In the 

 low dilutions of 1 part in 100 and 1 part in 200, ipecac shows 

 only feeble balantidicidal action, more or less but not all of 

 the protozoa being killed after exposure to its action for one 

 hour. Emetine hydrochloride, which has been proved by Ved- 

 der and Rogers to possess specific entamoebacidal properties 

 to an eminent degree, proves to be scarcely as balantidicidal 

 as ipecac. 



Quinine, which is a specific for malaria and which has been 

 frequently employed in the treatment of balantidiasis, is some- 

 what more active. The hydrochloride has killed all of the 

 balantidia in the dilution of 1 part in 100 in five to ten minutes, 

 in the dilution of 1 part in 300 in fifteen to thirty minutes, 

 in the dilution of 1 part in 400 in thirty to sixty minutes, and 

 in the dilutions of 1 part in 500 and 1 part in 600 in sixty 

 minutes. In dilutions of 1 part in 800 and higher, it is in- 

 active. The relatively feeble balantidicidal action of this drug 

 does not promise much success in its application to the treat- 

 ment of balantidiasis. 



These well-known protozoicidal substances having been proved 

 to possess feeble or no balantidicidal action, attention was 

 turned to the salts of the heavy metals. 



Copper sulphate, as is well known, displays a profound toxic 

 action toward certain of the lower organisms. It is said to 

 kill fresh-water algae in the remarkably high dilution of 1 part 

 in 1,000,000, and it has consequently been widely recommended 

 for the purification of water supplies. Its balantidicidal 

 strength, however, has proved to be only moderate. In the 

 dilution of 1 part in 1,000 it killed all of the balantidia in thirty 

 minutes. In higher dilutions it was inert. 



The salts of mercury possess eminent germicidal properties, 

 and they have been extensively employed not only as antiseptics 

 and disinfectants, but in the treatment of spirochsete and pro- 

 tozoan infections. The experiments with the chloride and the 

 iodide of mercury have demonstrated that they are also strongly 

 balantidicidal. In dilution as high as 1 part in 20,000 they 

 kill all of the balantidia within one minute. 



Silver is said to be one of the most toxic metals for bacteria 

 and protozoa, but unlike mercury to be comparativey innox- 

 ious for the mammalian organism. Tests of the balanti- 



