446 ELERY RONALD BECKER. 



achromatic reticulum on which are suspended fine basophilic 

 granules. The achromatic nuclear membrane is encrusted on the 

 inner surface by a fine beading of chromatin granules, which is 

 intermediate in coarseness between E. histolytica and E. coll. 

 A few binucleate individuals were found, but no division figures. 



Cysts were exceedingly rare, and only four eight-nucleate cysts 

 could be found; but these were well stained and suitable for 

 study. The shape is nearly spherical (Fig. 9) ; size, fifteen and 

 one half micra in diameter. Their especially characteristic 

 feature was the thickness of the cyst wall, which was in all 

 cases about one micron. This compares with a thickness of less 

 than 0.5 /I in E. histolytica and E. coli. The nuclei likewise 

 were fundamentally different from those of the other Endamcebx. 

 All the chromatin from the karyosome and periphery of the 

 nucleus appeared to have collected into a number of irregular, 

 deep-staining blobs. Some of these lay upon the nuclear mem- 

 brane, while others were farther in the interior of the nucleus. 

 The nuclei of the cyst measured about 2.8 micra in diameter. 

 In contrast to the free forms, where it is coarsely alveolar, the 

 cytoplasm of the cyst appeared granular. Chromatoid bodies 

 were absent, except for a few small dark staining splinter-like 

 bodies in the center of the cyst. The developmental stages of 

 the cyst were not found. 



It was upon the basis of thickness of the wall of the cysts, its 

 yellowish tinge, and the character of the cyst nuclei that a new 

 species was created for this amoeba. Were it not for this charac- 

 teristic cyst, it would be difficult to distinguish this from many 

 other Endama'bx; e.g., E. muris (Grassi, 1882) of the mouse 

 and rat. 



The w r riter in a previous paper (1922) pointed out that simply 

 finding a parasite in a host where it had not previously been 

 found was no valid reason for considering it a new species. 

 Especially is this true in the case of amoebae; for if, as Kessel 

 (1923) determined in his experiments, rodents can be infected 

 with the human amoeba?, it is probable that man can be infected 

 with the amoebae of rodents. Two points are so sufficiently clear 

 that they should not be ignored in future work in amoebae. 

 First, is the species being considered sufficiently different morpho- 



