OF THE INTESTINAL TRACT. 187 



mended for staining amoebae. The Wright stain and 

 the iron haematoxylin methods give the best results, 

 and if the latter is used the specimens should be fixed 

 while wet. 



Entamoeba tetragena does not show the difference 

 in the staining reactions of the ecto- and endoplasm 

 with Wright's stain which is so characteristic of well 

 stained preparations of Entamoeba histolytica. In 

 this species the cytoplasm stains a well marked blue, 

 when Wright's stain is used, while the nucleus, being 

 rich in chromatin, stains a ruby red or dark violet 

 color. In organisms which are undergoing division 

 the nucleus is often observed to be divided into two 

 spherical reddish bodies connected by delicate pinkish 

 strands of chromatin while further division is some- 

 times indicated by the presence of three or four masses 

 of red stained chromatin situated within the endo- 

 plasm. This species does not show the division of 

 the chromatin into delicate fibriles, distributed 

 throughout the cytoplasm, as does Entamoeba his- 

 tolytica, but elongated spindle-shaped masses of this 

 substance are frequently observed in amoebae under- 

 going reproduction. 



Reproduction. This species of amoeba reproduces 

 by simple division and by cyst formation with the 

 production within the cyst of four young amoebae. 

 Simple division is preceded by the mitotic division 



