186 
Charles E. Allen 
Wilson, M. 1908. Preliminary note on nuclear division in Mnium hornum. Ann. 
of Bot. Vol. XXII. ’ p. 328. 
1909. On spore formation and nuclear division in Mnium hornum. Ann. of 
Bot. Vol. XXIII. p. 141. 
1910. Pre limin ary note on the spermatogenesis of Mnium hornum. Ann. of 
Bot. Vol. XXIV. p. 235. 
1911. Spermatogenesis in the Bryophyta. Ann. of Bot. Vol. XXV. p. 415. 
Woodburn, W. L. 1911. Spermatogenesis in certain Hepaticae. Ann. of Bot. 
Vol. XXV. p. 299. 
Yamanouchi, S. 1908. Spermatogenesis, oögenesis, and fertilization in Nephrodium. 
Bot. Gaz. Vol. XLV. p. 145. 
Zimmermann, A. 1890. Über bisher nicht beobachtete Inhaltskörper des Assimila- 
tionsgewebes. Beitr. z. Morph, u. Physiol. d. Pflanzenzelle. Heft 1. S. 38. 
1893. Sammelreferate aus dem Gesamtgebiete der Zellenlehre. Beih. z. Bot. 
Centralbl. Bd. III. S. 206, 321, 401. 
Description of Figures, 
The figures were drawn with the aid of an Abbe camera lucida, the drawing 
being at the level of the base of the microscope; Zeiss 2 mm. objective, 1.40 N. A., 
and compens. oc. 18. Magnification, about 3800 x. 
Plate VI. 
Androgones of various generations. 
Fig. 1. Two sister cells of an early androgonial generation, each containing 
a polar plate; not long after their formation by the division of the mother cell. 
Figs. 2, 3. Resting cells; the polar plate curved about the nucleus. 
Fig. 4. The polar plate apparently dividing transversely into two daughter plates. 
Figs. 5 — 7. Stages in the divergence of the daughter plates; the beginnings of 
spindle formation. 
Figs. 8 — 10. The daughter plates in their final positions; the spindle rudiment 
well developed. In each case there are at one spindle pole two plates instead of one. 
Fig. 11. Two sister cells of a later androgonial generation, each containing a 
group of kinetosomes instead of a plate ; in the lower cell the kinetosomes seem to oe 
already separating into two groups. 
Fig. 12. A single cell containing a group of kinetosomes. 
Figs. 13 — 15. Stages in the Separation of the kinetosomes into two groups 
and the divergence of the latter. 
Figs. 16 — 18. The daughter groups of kinetosomes in their final positions; 
spindle formation. 
Figs. 19 — 24. Spirem formation in androgones of various generations; the nu- 
cleus swells until its membrane comes into contact with the polar structures. 
Figs. 25, 26. Androgone nuclei in the spirem stage. 
Figs. 27, 28. Androgone nuclei after the Segmentation of the spirem. 
Figs. 29 a — g. Stages in the gradual contraction of the nucleus and the dis- 
appearance of the nuclear membrane. 
