i8o RESEARCH IN PROTOZOOLOGY 



While the number of individuals examined was small and the 

 percentage of positive results must be interpreted with caution 

 owing to this small number, it is very evident that the cultural 

 method of examination of the feces gave a higher percentage of 

 positive results for Endamocba histolytica than any other method, 

 and these results have been confirmed by nearly four years' use of 

 this method at the Army Medical Center, where the cultural 

 method not infrequently picks up infections with this parasite 

 that are missed by the ordinary microscopic examination of the 

 stool. 



Our observations also demonstrated that the Locke-Serum 

 medium gave a higher percentage of positive results for E. his- 

 tolytica than the modified Boeck and Drbohlav Locke-Egg-Serum 

 medium. With the latter medium nine of the seventy-one individ- 

 uals examined showed this parasite in the feces, or 12.67%, while 

 with the Locke-Serum medium, eleven, or 15.49%, showed E. 

 histolytica in the cultures. 



As a result of nearly four years' use of the culture method in 

 the examination of stools for E. histolytica the writer believes 

 that this is the best method of making such an examination. It 

 invariably results in the demonstration of the parasite in all cases 

 in which it may be demonstrated by direct microscopic examina- 

 tion, and not infrequently it demonstrates the organism in cases 

 in which the direct microscopic examination had resulted nega- 

 tively. However, it is absolutely necessary that the culture media 

 be prepared as described and that the technique of inoculating and 

 examining the cultures noted in this contribution be followed. 

 Time and again, the writer has found that investigators have 

 failed to culture E. Jiistolytica because bacteriological technique 

 was followed in the examinations and inoculations, or other devia- 

 tions occurred from the proper technique. Wherever the proper 

 technique has been used the cultural examination of feces for 

 this parasite has been attended with excellent results but in this, 

 as in other laboratory procedures, experience is necessary, and 

 this cannot be acquired without devoting much time and attention 

 to the subject. 



In conclusion, it may be stated that the cultivation of Endamocba 

 histolytica has made possible great advances in our knowledge of 

 the life-history and biology of this important parasite of man 

 and has added a method of much diagnostic value to human 



