22.i Sellards and Leiva: Amoebic Dysentery 15 



Castela nicholsoni. — A few preliminary tests were made with 

 Castela nicholsoni (chaparro amargoso), but no satisfactory re- 

 sults were obtained. The preparation that was employed is 

 described later in connection with the treatment of dysentery in 

 man. It was extremely toxic for cats, 1 cubic centimeter per 

 kilogram, per rectum, proving fatal. Dosages that showed some 

 therapeutic effect were not tolerated well. If successful results 

 are to be obtained in treating cats with Castela nicholsoni, con- 

 siderable experimentation will be required to determine the most 

 favorable mode of its employment. 



The general results of these experiments are summarized 

 briefly in Table 2. 



In these investigations on the treatment of experimental 

 amcebiasis, quinine was found to possess one distinct advantage 

 over emetine, in that animals would tolerate the continued rep- 

 etition of effective therapeutic doses. However, it is obviously 

 unsound to draw any final conclusions from limited experience 

 with one or two strains of amoebae. 



From a clinical standpoint it is seen that the amount of qui- 

 nine necessary to control amoebic infection in cats is very large. 

 One animal (No. 29) eventually relapsed after receiving about 

 500 milligrams per kilogram of body weight. The minimal ef- 

 fective dose of quinine was not determined. Neither have we 

 tested the effect of quinine administered by mouth or by par- 

 enteral injection. 



In the treatment of patients with quinine, very dilute solu- 

 tions (1 to 5,000) are ordinarily recommended, the concentra- 

 tion being increased later to 1 to 1,000 or 1 to 500. We are 

 not aware of any evidence that this preliminary injection of 

 dilute solutions decreases the susceptibility of the bowel for the 

 more-concentrated injections. It is conceivable that the prelim- 

 inary treatment results chiefly in the loss of time and that, if 

 quinine is to be used, treatment might well be commenced with 

 stronger solutions. 



Throughout these experiments we have depended upon the 

 administration of emetine by rectum in rather strong solution. 

 Subcutaneous injection was discontinued on account of the very 

 unfavorable preliminary test. In those special patients in 

 whom emetine by intramuscular injection produces no response, 

 it would seem to us that rectal injection might be worthy of 

 consideration. Obviously, this mode of administration has not 

 met with favor as a routine procedure. Moreover, the simple, 



