:915] Swezij: Binarii and Multiple Fission in Hcxamitus 75 



The cytoplasm is granular and vacuolated, with no definite periplast 

 and no distinction between ectoplasm and endoplasm. Intra-vitam 

 staining with neutral red shows, with H. ovatus as well as H. intcsti- 

 nalis, the presence of a few, usuall.v three or four, deepl.v staining 

 granules in the cytoplasm of the posterior third of the bod.y. In the 

 living protoplasm a number of more or less highly refractive bodies 

 or granules are visible, scattered through the cytoplasm. In spite of 

 the lack of a structually differentiated periplast, the body is notably 

 uniform in outline, exhibiting few or no amoeboid tendencies. 



Binary Fission 



The splitting of the axostyles is the first sign of division in the 

 trophozoite and is accompanied by a more or less rounding up of the 

 body. The splitting is longitudinal, beginning at the anterior end and 

 including the posterior flagella (pi. 9, fig. 3), at the same time the 

 granules of the blepharoplast complex separate. The nuclei begin to 

 round up, as do also the chromatic masses which come to lie in the 

 centers of the nuclei, losing their connections with the blepharoplasts 

 (pi. 9, fig. 4). The entire structure appears at this time as two large 

 vesicular nuclei, each with a very large central spheroidal karyosome. 

 With the division of the blepharoplasts of each nucleus the two 

 daughter blepharoplasts, each with one of the daughter axostyles. move 

 180° apart to opposite poles of the nucleus, remaining connected by 

 a slender, darkly staining fibril, the paradesmo.se (pi. 9, fig. 4). One 

 flagellum is retained by one daughter blepharoplast. the other two 

 going with the other daughter blepharoplast. In this as well as in 

 the other forms of Hexamifus luider observation a striking decrease 

 in the amount of chromatin material in the blepharoplast complex 

 takes place before the division of that body and the migration of the 

 daughter blepharoplasts to the poles of the nuclei. No chromatin 

 seems to appear, as such, in the cytoplasm at this time, the extruded 

 material probably being absorbed. 



When the new positions have been taken up by the daughter 

 blepharoplasts, the karyosomes begin to assume an irregiilar appear- 

 ance (pi. 9. fig. 5), and .soon break up into a number of granules 

 which later form a segmented spireme or skein (pi. 9. fig. 6). In .iust 

 what way this changes into chromosomes has not been observed. 



During this process the spindle fibers begin to form between the 

 daughter blepharoplasts, which here function as centrosomes. The 



