4 The Philippine Journal of Science 1923 



In the absence of any bile salts, a specimen of cholalic acid 

 was neutralized with sodium hydroxide. Its toxicity was 

 rather low. 



Papaverine was used as the hydrochloride, a salt which is 

 only moderately soluble in water (about 1 to 37) and very 

 much less soluble in physiological saline. Even the higher 

 dilutions (1 to 5,000) prepared with this culture medium showed 

 extensive precipitation. The results obtained were irregular, 

 and duplicate tests showed considerable variation. 



Benzyl benzoate is almost insoluble in water. Nevertheless, 

 its suspensions in this culture medium inhibited the growth of 

 amoebae to a remarkable degree. Simpler benzene derivatives, 

 ordinarily used to prevent bacterial decomposition, showed no 

 such effect. Abundant growth of amoebae was permitted by 

 benzene itself in a suspension of 1 to 1,000; by toluene, at 1 

 to 1,000; and by xylene, at 1 to 10,000. 



Tests with neosalvarsan are necessarily unsatisfactory, since 

 solutions of this drug oxidize rapidly and increase in toxicity 

 at room temperature. However, a dilution of 1 to 5,000 permit- 

 ted free growth of amoebae. In one of the tests a solution of 

 neosalvarsan was shaken vigorously for fifteen minutes before 

 diluting with the culture medium. The amcebse grew just as 

 well as in the corresponding dilutions that were not shaken. 

 As would be expected, this initial increase in toxicity produced 

 by shaking could not be detected by tests extending over a 

 period of from one to three days. 



An active principle of Castela, nicholsoni was prepared by a 

 method previously described. (14) This product was only slightly 

 soluble m water. However, a dilution of 1 to 5,000 was usually 

 sufficient to inhibit amoeba?. 



Tinosporarumphii Boerlage contains an extraordinarily bitter 

 pnnC i ple ' 3 1S plant is know * to the Tagalogs as makabuhay, 

 signifying Giver of life." It is widely used in the Philippines. 

 In India, there is a related species, T. cordifolia Miers- this 

 name is given m the Indian Pharmocopoeia, and the plant is 

 used m the treatment of malaria and syphilis. A bitter prin- 

 ciple of the Philippine species was prepared by A. H Wells 

 in charge of the division of organic chemistry of the Bureau of 

 Science. It possessed only an insignificant action against the 

 cultures of this amoeba. 



In chemotherapeutic work in amoebic dysentery, tests of tox- 

 icity of a drug for limax amoeba* are not without value for 



