2 The Philippine Journal of Science 1923 



amoebae in vitro; II. Results obtained in treating cats infected 

 with Entamoeba histolytica; and III. Clinical observations. 



I. EXPERIMENTS UPON CULTURAL AMCEB^E IN VITRO 



Cultural amoeba.— Considerable difficulty is encountered in 

 testing and interpreting the effect of various agents upon 

 amoebae in vitro. The chief obstacle lies in the absence of any- 

 reliable method for the artificial cultivation of the pathogenic 

 amoebae. Indeed, it is not yet established that multiplication 

 of the entamoebas has been induced in vitro. Realizing these 

 deficiencies, Vedder tested the effect of emetine on the non- 

 pathogenic cultural amoebae of the limax group. Bouillon di- 

 luted with water (1 to 20) was used, and the substance to be 

 tested was added directly to this fluid culture medium before 

 inoculation. Pyman and Wenyon(H) carried out similar ex- 

 periments, using a solid agar instead of a liquid medium. These 

 authors raise the question as to whether the drugs incorporated 

 in the medium distribute themselves uniformly between the 

 agar and the slight amount of fluid of synaeresis on its surface. 



Entamoeba histolytica.— Many observers have tested, by direct 

 microscopic examination, the effect of various substances on 

 E. histolytica. This parasite, however, degenerates spontane- 

 ously, and with great rapidity, on removal from its host. The 

 results with a given drug are often inconstant and irregular. 

 As would be expected, the data of various workers are often 

 divergent. Dale and Dobell report an exceptional instance in 

 which amoeba- survived the action of emetine at 1 to 100 for a 

 period of one hour. Rogers found that a dilution of 1 to 100,000 

 caused immobilization in a few minutes, the amoebae being ap- 

 parently dead. 



The work here reported has been conducted entirely with a 

 limax type of amoeba. The substances tested were emetine, 

 quinine, neosalvarsan, cholalic acid, benzyl benzoate, papaverine, 

 Castela nicholsoni Hooker, Tinospora rumphii Boerlage and 

 some miscellaneous control substances. The amoeba used was 

 isolated originally from the stool of a healthy person. The stock 

 cultures were kept on the usual agar medium using 15 grams 

 of agar and 15 cubic centimeters of normal soda per liter of 

 water. No attempt was made to isolate a strain of this amoeba 

 from a single cell nor to identify the mixture of bacteria grow- 

 ing with it. A fluid medium was prepared as follows: Peptone 

 1 gram; sodium chloride, 1 gram; lactose, 1 gram; artesian 

 water, 1,000 cubic centimeters. Varying dilutions of the agents 



