AMCEBJS OF THE INTESTINAL TRACT. 101 



upon a warm-stage or under the incubator-micro- 

 scope or in wet-fixed preparations stained with iron 

 haematoxylin. I have been able to follow almost every 

 developmental stage as described by Schaudinn and 

 the following description of reproduction in Enta- 

 mceba coli is based upon that given by Schaudinn and 

 upon my own observations. 



In reproduction by simple division, which is not 

 infrequently observed in the feces, the following 

 phenomena may be demonstrated in the living 

 organism: the nucleus elongates, the nuclear mem- 

 brane becoming thinner and less refractile while the 

 chromatin, which is visible as brightly refractile dots 

 or granules, becomes concentrated at each pole of the 

 nucleus. After the nucleus has become much 

 elongated a constriction develops near the centre and 

 finally division occurs, two nuclei being produced. 

 Coincident with the elongation and division of the 

 nucleus the protoplasm of the amoeba becomes less 

 granular and a constriction appears which deepens 

 and finally becomes complete after the division of 

 the nucleus. In this way two amcebse are formed and 

 in stained specimens the division of the chromatin and 

 the nuclear changes can be followed, the chromatin 

 staining a bright red with Wright's stain. If iron 

 haematoxylin be used, after wet-fixation, clear evi- 

 dences of mitosis are frequently observed. 



