66 THE FISSIGEMMATION OF STENTOR. 



takes place at about midway between the top and base of the 

 body, (for instance, at cv 1 , fig. 30,) and the upper end of the lower 

 portion soon develops a globular cavity like the original one (cv) 

 Soon after this there appears, directly to the right of the new 

 globular vesicle, and exactly in the middle line of the ventral 

 side of the body, a shallow pit, and around this pit a semicircle 

 of vibratile cilia. The pit, which is the future mouth, gradually 

 deepens, and a funnel-shaped cavity, the throat, is presently 

 formed, which extends inwardly and backwards in the same rela- 

 tion to the body as does the oesophagus of the old head. At the 

 same time, the semicircle of cilia increases in length, and takes a 

 spiral course, in one turn about the new mouth, and then passes 

 around to the left of the body, and obliquely forward until it 

 reaches a point just behind the edge (c) of the disc, and mid- 

 way between the ventral line and the left side. 



This, I beg you will take note, is all a new growth, or bud- 

 ding, as it is called ; and as yet no trace of external self-division 

 is visible. But that follows now at once, and in about two 

 hours, as I observed on one occasion, the separation is com- 

 pleted. For this purpose, the constriction commences consider- 

 ably in front of the new mouth, and is most conspicuous, at the 

 outset, on the left side. This seems, as it were, to push the new 

 row of cilia further around toward the back, and at the same 

 time obliquely toward the tail. When the constriction has passed 

 across the body, from left to right, for about two thirds the way, 

 the row of cilia has retreated, and extended around the body 

 almost to its starting-point, so that it forms a broad open spiral, 

 (fig. 31, c 1 ,) which has nearly the same obliquity as that around 

 the old disc. By this time the ribbon-shaped reproductive organ 

 (w, w 1 , w 2 ), at the right of the mouth (w), has also divided. This 

 is the condition in which the Stentor is represented in this figure, 

 (fig. 31,) as it swam freely about in a partially closed state. 



From this time onward, until separation, very little change 

 takes place in the organization ; the constricting simply narrows 

 the yet remaining connection (a 1 ), and, as this is done, the two 

 ends of the broad spiral (c 1 ) of cilia gradually approximate each 



