IV 



A PARASITE OF AM(EBA 



WHILE examining some amoeba cultures, one of 

 us (A.H.D.), noticed a peculiar black- looking, 

 diamond-shaped body with a central dot (fig. 31), 

 moving sluggishly about in the endoplasm of one 

 of the amoebae. Similar bodies, usually round and 

 often in pairs, were found in other amoebae from 

 the same culture, and a single one was occasionally 

 seen dividing and separating into two. These 

 bodies were rather scanty, and could not be 

 recognised with certainty in the medium outside 

 the amceba. Subcultures of amoebae which con- 

 tained these bodies did not thrive on 2-per-cent. 

 agar as they usually do, many in fact dying out 

 completely, and others degenerating, becoming 

 sluggish, highly vacuolated, and the contractile 

 vacuole motionless (fig. 32). Many of the food 

 vacuoles were enormously distended, and con- 

 tained large numbers of granular bodies which 

 were in a state of violent agitation. The out- 

 standing feature, however, was the absence of any 

 attempt of the amcebse to encyst, in spite of the 

 fact that they were being destroyed wholesale. 

 The persistence of this morbid condition in every 



culture interfered with our experimental progress 



102 



