5 1 4 JOHNSON. [Vol. VIII. 



unimportant duty of serving as connectives for the nodes. 

 The rate of constriction at the different commissures is by no 

 means uniform in the later stages of the process, and some- 

 times alternate commissures become developed sooner than 

 the intermediate ones (Fig. 45), thus producing double nodes, 

 which are of very frequent occurrence even in adult Stentors. 



The mode of meganuclear division above described is un- 

 doubtedly typical for all Stentors having a moniliform or rod- 

 shaped nucleus, and, indeed, for such meganuclei wherever they 

 occur. It is, however, by no means essential that the actual 

 division should be achieved in just this manner, although the 

 process is always upon the same general plan : condensation, 

 elongation, renodulation. The variation lies in the time at 

 which division is interposed, and in this respect I have noted 

 the following cases: 



(i) Division may be deferred until the close of the phases, 

 as in the foregoing description. 



(2) It may occur at time of maximum coalescence, (Fig. 

 46 a, b). 



(3) It may take place during the coalescence of the nodes. 

 (Fig. 47, a-d.) 



(4) The nucleus may be in two equal or nearly equal parts 

 previous to fission, and no division whatever take place. But 

 if the parts are very unequal (as in Fig. 35) division will occur 

 as in (i) or (2). 



Fig. 46, a-g represents a series drawn from the living nucleus, 

 showing the phases when the nucleus divides at the moment of 

 greatest condensation. The division was obviously unequal. 

 Immediately after division both parts began to elongate, 

 and soon came into contact {d). The larger, posterior piece 

 lengthened more rapidly than the smaller, anterior portion. 

 When the two daughter-nuclei pressed closely together at the 

 point of contact, even bulging at that point owing to mutual 

 pressure, I watched carefully to see whether fusion would take 

 place. But it occurred neither in this instance nor any other 

 in which I followed the process in the living meganucleus; 

 they finally drew apart always at the very point where they 

 had been in contact. Coalescence was evidently prevented by 



