Aster diet hemisphaerica, Beauv \ 
539 
Summary. 
The last division in the spermatogenous cells may be oblique, as in 
Marchantia , but it is not always so. 
The number of chromosomes is eight. 
Prior to the formation of the spindle, small, dense cytoplasmic caps 
appear on opposite sides of the nucleus near the positions which will be 
occupied by the poles of the future spindle. These caps arise de novo ; they 
are neither permanent cell-structures nor are they centrosomes. 
The blepharoplast arises near the plasma membrane as a newly-formed 
structure. 
The most completely developed sperm shown consists of a curved, 
club-shaped part, the nucleus, tapering to a slender point which is continued 
by the thread-like blepharoplast bearing two cilia at its anterior end. 
EXPLANATION OF PLATE XX. 
Illustrating Professor W. L. Woodburn’s paper on Spermatogenesis in 
Asterella liemcspliaeri, Beauv. 
Figs, i to 17 pertain to the last nuclear and cell division in the spermatogenous cells (androcyte 
mother-cells) in the antheridium. 
Fig. 1. Cell with nucleus in resting condition. 
Fig. 2. The chromatin has become more coarsely granular. A large nucleolus lies in a colourless 
cavity. 
Fig. 3. The chromatin shows a tendency to accumulate about the nucleolus. 
Fig. 4. The entire nuclear content has contracted near the centre of the nucleus. 
Fig. 5. The nucleus has become elongated. 
Figs. 6 and 7. The formation of the chromosomes. 
Figs. 8 to 13. The formation of the spindle. In Figs. 8 and 9 densely staining caps of cyto- 
plasm appear on opposite sides of the nucleus. In Fig. 10 the caps have almost disappeared. 
Fig. 11 represents a pointed spindle, while in Figs. 12 and 13 the poles are broadly truncated. 
Figs. 14 to 17. Telophases. 
Figs. 18 to 2 7. Transformation of the sperm initial into the mature sperm. 
Fig. 19. The plasmic contents have rounded up. A dense body, probably the primordium of 
the blepharoplast, is seen near the plasma membrane. Finely granular material is indicated between 
the cell-wall and the rounded protoplast. 
Figs. 20 and 21. Later stages. 
Figs. 22 and 23. The blepharoplast is now elongated and thread-like; the nucleus is oval or 
elliptical. 
Figs. 24 and 25. Two young sperms of a single androcyte. 
Figs. 26 and 27. The cilia are present. 
P p 2 
