CULTIVATION OF PARASITIC AMOEBAE. 59 



be present and it is this fact which has led to the 

 mistaken idea that the parasitic amoebae are easily 

 cultivated. 



Regarding this subject Braun and Liihe, in their 

 latest work upon parasitology, published in 1910, say : 

 ' It must be borne in mind, however, that not all 

 amoebge can be cultivated upon solid media, and that 

 the varieties which are parasitic in mammals have 

 never been successfully grown outside of the tissues 

 of their host." This statement is concurred in by 

 the writer, for I have never been able to obtain any 

 amoebae upon cultural material which resembled those 

 parasitic in man, nor have I ever seen amoebae cul- 

 tivated by others which agreed in either their mor- 

 phology or their methods of reproduction with the 

 parasitic species occurring in the human host. All 

 cultivated amoebae that I have observed possess a con- 

 tractile vacuole and otherwise resemble in their mor- 

 phology the common free-living species. The success- 

 ful production of dysenteric lesions in animals by the 

 use of cultures of amoebae obtained from dysenteric 

 feces proves nothing, as the material could easily be 

 contaminated by the minute spores of Entamceba 

 histolytica, or encysted forms of other pathogenic 

 species, or by bacteria capable of causing dysentery. 



In regions where free-living amoebae are common, 

 as in the tropics, it is not at all difficult to cultivate 



