THE CULTIVATION OF ENDAMCEBA HISTOLYTICA 179 



in small numbers at certain intervals and unless this is done the 

 strain will be lost. Use a one cubic centimeter pipette with a good- 

 sized bore and transfer as much of the sediment as possible. In 

 our experience the number of amoebae vary considerably in the 

 cultures and there is some indication of a more or less regular 

 cycle in the growth of the organisms in culture so far as number 

 is concerned. Upon certain days the amoebae are so few that one 

 almost believes the organisms to have perished but on succeeding 

 days they will again become very numerous. 



The Vahie of the Cultivation of E. histolytica in Diagnosis. 

 In 1922, Hegner and Becker called attention to the value of cul- 

 tures in the diagnosis of infestation of the intestine with flagellates, 

 and, in 1926, St. John demonstrated the value of the cultivation of 

 E. histolytica from the feces in the diagnosis of amoebiasis, obtain- 

 ing a higher percentage of positive results by culture than by the 

 direct microscopic examination of the feces. In 1927, the writer 

 and St. John published the results of the examination of seventy- 

 one individuals, using direct microscopical examination of the 

 feces, cultural methods, and sedimentation tests, in comparison, one 

 with another. The following tables illustrate the results obtained 

 with these various methods. 



Table i. Results with Direct AIicroscopical Examination 



Per Cent 

 Species of Amoeba Positive Negative Positive 



Endamocba histolytica 6 65 8.45 



Endamcuba coli 8 63 11.26 



Endamoeha nana 2 69 2.81 



lodamoeha williamsi 3 68 4.21 



Table 2. Results with Cultural jMethods 



Per Cent 

 Species of Amoeba Positive Negative Positive 



Endamoeha histolytica 11 60 I549 



Endamoeha coli 21 50 29.57 



Endamceba nana 9 62 12.67 



lodamoeba unlliamsi 4 67 5.63 



Table 3. Results with Sedimentation Test 



Per Cent 

 Species of Amoeba Positive Negative Positive 



Endamoeba histolytica 9 62 12.67 



Endamooba coli 12 59 16.90 



Endamosba nana 3 68 4.21 



lodamceba williamsi 3 68 4.21 



