l 5 4 BOTANICAL GAZETTE [march 



spermatid does not grow further, the nucleus and the blepharoplast 

 increase in size during this metamorphosis, and the space occupied 

 by the cytoplasm consequently gradually diminishes. The blepharo- 

 plast, now round in shape, lies very close to the nucleus and elongates 

 along its spherical surface (figs. 23, 24), so that the surface view of the 

 blepharoplast at this time shows a rhomboidal outline (fig. 23) and its 

 cross-section is crescent-shaped, the concave surface being in close 

 contact with the nuclear membrane (fig. 24). The elongation of the 

 blepharoplast now proceeds farther. Fig. 26 shows the section of the 

 blepharoplast at this stage, cut parallel with the axis of elongation. 

 The cross-section of the blepharoplast is shown in fig. 27, and a part 

 of the structure viewed from the surface is given in fig. 25. 



Until this time the blepharoplast is alike at both ends, and no 

 modification was ever observed in the structure of the nucleus ; but 

 soon after the blepharoplast has elongated into a semicircular band, a 

 very complicated modification follows in both nucleus and blepharo- 

 plast. One end of the blepharoplast becomes wedge-shaped and 

 loosely laid along the spherical surface of the nucleus (fig. 28), while 

 the other end, which still remains pointed, comes into close contact 

 with the nucleus and finally coalesces with it (figs. 28, 29). The elon- 

 gating blepharoplast now takes a spiral direction and has a tendency 

 to form a coiled ribbon-like structure. 



While the foregoing modification is occurring in the blepharoplast, 

 the nucleus undergoes a characteristic transformation of form. The 

 distribution of the ragged chromatin clumps within the nucleus be- 

 comes irregular ; at certain regions of the nuclear cavity they become 

 grouped very densely; while in other parts the chromatin substance 

 is scattered. The nuclear membrane, very delicate at this time, 

 seems to be easily influenced by any change which occurs in the 

 interior of the nucleus, so that the region where the chromatin clumps 

 are densely crowded may protrude above the spherical surface of the 

 nucleus, while the region with scanty chromatin material may form 

 a depression or furrow. This unevenness in the form of the nucleus, 

 brought about by the irregular aggregation of the ragged chromatin 

 clumps in different regions of the interior, develops in such a direc- 

 tion that the nucleus becomes metamorphosed into a coiled structure. 



When the nucleus has almost assumed the coiled form, one end. of 



