542 CLASSIFICATION AND MORPHOLOGY OF AMEBA' 



of amebse. If microscopic examination reveals amebse, one or more 

 loopfuls of the surface fluid containing them is streaked over the 

 surface of the set agar in the Petri dishes. In the course of from 

 six to forty-eight hours the plates are to be examined under a low 

 power of the microscope in the same manner as for bacterial colonies. 

 If the amebse have multiplied, at they usually do, they can be recog- 

 nized under the low power of the microscope as highly refractive 

 bodies. From such plates others can be inoculated by making trans- 

 plants and again streaking the agar on the surface. In trying to obtain 

 a growth of intestinal amebse it is necessary to streak small particles 

 of feces, best some mucous flocculi picked up with the platinum loop 

 over agar plates, because such parasitic amebse do not multiply as 

 easily in fluid as do saprophytic amebse from ordinary outside sources. 



FIG. 184 FIG. 185 



Ameba from a case of tropical dysentery Encysted forms of an ameba from an old 



in man. Twelve hours' culture. (Musgrave culture. (Musgrave and Clegg.) 



and Clegg.) 



When amebse grow after such an inoculation several kinds may be 

 present in addition to a variety of bacteria. It is, however, necessary 

 to isolate one kind of ameba and to cultivate it with one known kind 

 of bacterium. No one has ever succeeded in cultivating amebse alone 

 in absolutely pure culture, because they evidently need for their 

 nutrition live, unchanged proteid material. The best that has so 

 far been accomplished has been to obtain amebse in symbiotic 

 community with one known species of bacterium. Such a culture 

 has been called by Frosch "a mixed pure culture of amebce." Mus- 

 grave and Clegg succeeded in getting such pure cultures in a manner 

 described by them as follows : 



"Select a plate culture on which the parasites are well distributed 

 and after removing the cover, place the plate with the open side up 

 on the stage of the microscope. By searching the edges of the growth 



