EAND : XERVOUS SYSTEM OF LUMBRICID.^. 129 



cells. The second fact is the presence of considerable loosely aggregated, 

 rather granular material outside the limits of the constricted figure. 

 As the volume of the constricted figure is much less than that of the 

 barrel-shaped figure which precedes it, and as the material in question 

 is mainly in the region formerly occupied by the barrel-shaped figure, it 

 is reasonable to conclude that this material is some of that originally 

 contained within the limits of the larger figure. 



In Figure 28 one chromatic mass has been cut away. The centrosome 

 of the other pole is not visible, probably because of the obliquity of the 

 axis. Something of the lightly stained polar region can be seen. The 

 old cell membrane has degenerated to a less extent than in Figure 27. 

 A distinct equatorial membrane is present, and the interzonal filaments 

 are sharply constricted. Outside the constricted figure is some loose 

 material, as in Figure 27, and a few fibres from the chromatic mass 

 mark the outlines of the former barrel-shaped figure. 



Figure 29 is a reconstruction. The left chromatic mass was cut away 

 from the rest of the figure, being found in an adjacent section. The 

 old cell membrane is indistinct. The equatorial membrane is clearly 

 present. The interzonal filaments are sharply constricted, and there is 

 a suggestion of a " Zwischeukorper." There are some traces of fibres 

 outside the constricted figure, but, except for these, the space outside the 

 figure is almost clear. The chromatin appears enclosed in a membrane, 

 and the daughter chromatic masses show considerable increase in size. 

 The chromatin is in the form of large granules. At the polar side of 

 the left chromatic mass (nucleus ]), the lightly stained region and the 

 centrosome are to be seen. These could not be seen in the other daugh- 

 ter cell, perhaps because of the position of the axis. The condition of 

 the chi'omatiu in this case is much more advanced than ordinarily 

 when the interzonal fibres are still present. 



In Figure 30 the chromatic masses are in much the same condition as 

 in Figure 27. Owing to the obliquity of the axis of the right daughter 

 cell, the centrosome is not to be seen. The old cell membrane is fairly 

 distinct in some regions, but quite lacking in others. The interzonal 

 filaments are sharply constricted. There is, again, a suggestion of a 

 Zwischeukorper, although the concentration of the fibres may account 

 for the darkness at their equatorial region. The important points to 

 be noticed are, first, that the daughter-cell bodies outside the limits of 

 the constricted figure are practically clear, and, secondly, that there is 

 no trace of an equatorial membrane. The constriction of the old cell 

 outlines and the constriction of the interzonal filaments would indicate 

 that the equatorial membrane had been formed and has disappeared. 



