26 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



parallel differentiation of a new peristomal spiral and mouth 

 taking place in the two individuals during the later stages. 

 The exact details of this process have thus far eluded 

 observation. 



A contractile vacuole appears in each individual in the 

 stage shown in fig. 42, v. 



One individual with two buds was observed alive, but 

 unfortunately escaped from the preparation in the process 

 of fixation (fig. 84). 



In only two cases was division of the micronucleus seen 

 in fresh material (fig. 34, t^, methyl-green acetic). The 

 two micronuclei appeared as equally and evenly stained 

 spheres connected by two colorless membrane-like lines 

 in optical section. Careful searching through hundreds 

 of sections gave the very striking series shown in fig. 67, 

 a—j, indicating a variety of mitotic division, but too incom- 

 plete for satisfactory interpretation. The first indication 

 of approaching division of the infusorian is an enlarged 

 and coarsely granular appearance of the micronucleus (<5) ; 

 this continues to increase in size, and the chromatin as- 

 sumes the form of two crescent-shaped bands held in 

 place by a delicate fibre attached to each band and to the 

 surrounding membrane ((?) ; division of the chromatin 

 bands within the membrane is indicated in ^>-, while in the 

 stage shown in h the membrane has disappeared and we 

 have three (?) chromatin bands at each end of a spindle, 

 each two daughter bands being connected by a single fibre. 

 The bands now unite to form compact oval masses still 

 connected (?) ; the two new micronuclei round up, the 

 spindle fibres disappear, and a membrane is formed around 

 each (y). 



Figures 56, 57 and 59 show the relation of e, h and i 

 to the macronucleus. Figures 58, 6oh, 62 and 63 were 

 from material fixed with Boveri's picro-acetic, which gives 

 a somewhat different appearance to the nuclear contents, 

 the chromatin granules showing a tendency to arrange- 

 ment in longitudinal rows during the various stages of 

 nuclear division. 



