NUCLEAR DIVISION OF NOCTILUCA. 249 



Still later stages are sliown in Figs. 11 and 12, Plate XII, of 

 my earlier paper ('94, c), in which the tentacles are represented 

 as consisting of ^olasraa different from that of the centrosphere, 

 but the clear ajDpearance of the tentacles in these figures is not 

 due to any difference in their constituent plasma, but to ad- 

 vanced differentiation of the contents of the tentacle into its 

 usual striated structures on the ventral side, as I have now 

 ascertained from my original notes. The same thing is also to 

 be seen in my new preparations made this year. Fig. 48 re- 

 produced from such a preparation, and represents a part of the 

 central plasma of an individual in the last stage of division, the 

 narrow cytojolasmic bridge joining the daughter-individuals hav- 

 ing been severed by the action of Flemming's fluid with which 

 the animal was killed. Besides the nucleus which is very 

 strongly coloured with iron-hœmatoxylin, there are to be ob- 

 served the teeth, the tentacle, the centrosphere, and the flagellura. 

 The tentacle in this specimen is already striated on the ventral 

 side and appears much lighter in colour than the substance of 

 the centrosphere, from the centre of Avhich it springs. In the 

 same preparation is to be seen also the fiagellum arising from 

 the same area as the tentacle, although development from the 

 substance of the archoplasm, as observed in the case of the ten- 

 tacle could not be followed out in it. 



Into the first formation of the centrosphere and its relation 

 to the tentacle in the individuals that are going to divide, I 

 have as yet obtained no clear insight. Their relative position 

 seems to be subject to considerable variation. Indeed, it is very 

 probable that a centrosphere, disappears by differentiation into 

 the substance of the tentacle, and is therefore not a permanent 

 organ. If this be so then a new centrosphere must be formed 



