ZooL— Vol. III. ] STE VENS— CILIA TE INFUSORIA . 2 5 



Staining the animals most excellently, — and mounted tem- 

 porarily in glycerine. Certain unusually large forms showed 

 a shortened condition of the oral cilia, oblique position of 

 the nucleus, and two micronuclei near the macronucleus 

 (fig. 37)- In the next stage the macronucleus was decid- 

 edly elongated, and contained a suggestion of an equatorial 

 plate; the two micronuclei were located at or near the poles 

 of the macronucleus, and indentations already indicated 

 the line of division of the cell body (fig. 39). In all the 

 cases observed, the second micronucleus passed forward 

 along the aboral side of the obliquely placed macronucleus 

 to its oral pole. In later stages the central portion of the 

 cell elongates and is differentiated unsymmetrically to form 

 a new peristomal portion for one animal and a new aboral 

 portion for the other (figs. 40-45). Meanwhile the macro- 

 nucleus divides with indications of a primitive variety of 

 karyokinesis. In a few cases something like an equatorial 

 plate has been observed in both m toto preparations and 

 in sections, and later stages show two distinct plates with a 

 fibrillar appearance between them. The chromatin, during 

 division, appears in the form of coarse granules rather than 

 as distinctly individualized chromosomes. 



Separation of the nuclear mass is complete for some time 

 before the membrane divides, it being drawn out in the 

 form of a narrow tube or a thin thread between the two 

 daughter nuclei (figs. 43 and 44). Finally, the vestiges 

 of the connecting thread disappear, the two nuclei round 

 up, and the narrow bond holding the two individuals to- 

 gether breaks; the result is two daughter animals alike in 

 every respect (fig. 46), with the exception of the position 

 of the micronucleus. The point of separation of the two 

 cells gives the non-ciliated aboral spot, described above, 

 in one individual, while in the other no trace remains. 

 The young Boveria is short and broad compared with adult 

 specimens, and the nucleus is rounded or elongated trans- 

 versely (fig. 46). 



During the early stages of division, the original peristome 

 becomes inconspicuous, its cilia nearly as short as those of 

 the body system, and the mouth and pharynx disappear, 



