ENDAMCEBA C1TELLI SP. NOV. 451 



each other. Finally, the deeply-staining mass of granules be- 

 comes compact and uniformly solid (Figs. 2, 3, 8, 15, 16, etc.). 

 By this time the fluid content of the vacuole has disappeared 

 and the wall of the Sphxrita is contiguous with the cytoplasm of 

 the amceba. The development then proceeds as described above. 



The writer realizes that it may be objected that two organisms 

 have been confused in this cycle, and that what has been in- 

 terpreted as the infective form of the Sphxrita is in reality a 

 bacterium ingested as food. This danger was a cause of con- 

 siderable anxiety, and it was not until a large amount of material 

 was studied that the writer was convinced of the specific identity 

 of the two forms. A careful study of such appearances as in 

 Fig. 8 (where one finds a perfect series from the bacterium- 

 like form to the early uninucleate form, unmistakably that of 

 Sphxrita) brings conviction of the transition from one form to 

 the other. The only gap in the life-history is the failure to 

 observe convincing stages of the growth of the spores into these 

 larger bacterioid forms. It is to be expected that such stages 

 would be exceedingly difficult to find, considering the amount 

 of the faecal mass in proportion to the number of spores. The 

 writer has observed, however, the smaller dumb-bell-shaped 

 dividing spores resembling the smaller individual in Fig. 10 

 within an old sporangium from which all but a few of the spores 

 had been expelled. 



The extracellular development of 5. endamcebx differs in several 

 important respects from that described by Dangeard for the 

 forms which he found in free-living flagellates and rhizopods. 

 Here the zoospores became elongated and flagellated as they left 

 the sporangium. Then they united in pairs, as in conjugation. 

 The spores studied by the writer were never flagellated when 

 found outside the amceba, and no conjugation of spores was 

 observed, although what appeared to be dividing spores indicat- 

 ing a free multiplication cycle were often found. 



As in the case of Sphxrita living in other protozoa, this 

 Sphxrita is mildly pathogenic to its host. Most parasitized 

 amoebae exhibit no degenerative changes of any kind (Figs. 2-6, 

 8). Some of the more heavily infected ones, however, manifest 

 the ill-effects of parasitism by abnormal nuclear appearances 

 (Fig. 7) . The karyosome becomes swollen and irregular in shape. 



