276 Multiplication by Fission in Stentor Mülleri. [May, i 
that the ciliary motion was extending from the disk, at the point 
of depression in its horseshoe shape, down along the body about 
one quarter of its whole length, and this gradually became more 
marked until the Stentor presented the appearance shown in out- 
line in Figure 16 a. The 
portion of the body immedi- 
* ately under the disk swelled 
slightly, and the general 
form somewhat resembled 
>=" the flower of the calla lily. 
The next change noticed 
was that at the bottom of 
the slit in the side the open- 
ing took a rounded form, so 
that the chain-like motion of the cilia looked (as a member of my 
family expressed it) as if a chain were running over a little pulley, 
and the cilia made a continuous fringe around the disk, down the 
body, and around the circular end of the slit, as shown in Figure 
160. j 
The body now began to show a protuberant swelling immedi- 
ately under the small circular opening at the lower end of the cil- 
iated slit, and in a few minutes this enlargement equaled in diam- 
eter the previous thickness of the body of the Stentor at this point, 
thus doubling its size at the point of greatest expansion. The 
protuberance was distinctly on one side of the body, and appeared 
as an excrescence, the ciliated line running out to its apex, and 
the Stentor now showing the appearance outlined in Figure 16. 
The swelling continued to increase, involving gradually the 
whole circumference of the body of the animalcule, the upp 
side of the protuberance assumed a sharper angle to the longitu- 
dinal line of the body, becoming more disk-like, while the line 
of the cilia enlarged so as to show an approach to the general 
form of the original head of the Stentor, the new oral openmg 
gradually enlarging and deepening. Figure 16d shows the ap- 
pearance about a quarter of an hour later than that represent 
by Figure 16 c. 
The slit line between the two disks now disappeared, and at 
the end of another quarter of an hour the upper portion of the 
body was attached to the lower by a connection no thicker than 
the tail of the original had been, though in each the disk was 
about one third smaller than the original disk, and the slope 
from it to the smaller part of the body below was much lest 
