4 i 9 
of Preissia quadrata (Scop.), Nees . 
through dense alveolar cytoplasm (Fig. 6). No well-defined hyaline zone 
around the centrosome was recognizable at this stage. The region towards 
which the fibres converge varies in appearance. It has been variously 
described as a protoplasmic structure of minute size without a centrosome 
(Farmer and Reeves, 1894); a hyaline sphere containing a centrosome in 
its centre (Farmer, 1895); a centrosphere-like region of dense protoplasm, 
the interior of which is frequently granular (Davis, 1901); and a body con¬ 
sisting of the same substance as the astral rays (Chamberlain, 1903). Fig. i 
shows the nuclear membrane of the egg somewhat drawn out to a point 
where the centrosome lies upon it. The egg nucleus is thus apparently 
responding to the influence of the centrosphere at one pole. The nucleus 
of the antherozoid has progressed in the cytoplasm of the egg so that it lies 
partly beneath the nuclear membrane of the egg nucleus. Two of the rays 
from the centrosphere nearest it touch its membrane. 
Centrosomes and asters are readily demonstrable in the sporophyte of 
P. quadrata. Fig. 7 represents a four-celled embryo. Part of the nucleus 
and the other centrosphere of each cell are in another section. 
From my studies it is evident that centrosomes as definite granular 
bodies are present not only in the divisions just preceding spermatogenesis 
and, as blepharoplasts, during metamorphosis, but also in the fertilized egg 
at the time when the pronuclei are paired. I have further observations soon 
to be published on the behaviour of the centres during the earlier stages of 
the fusion of the antherozoid with the egg. 
Literature cited. 
Allen, Charles E.: Cell Structure, Growth, and Division in the Antheridia of PolytrichutH, 
juniperinum. Archiv fur Zellforschung, Bd. viii, i. Heft, pp. 121-78. 1912. 
Belajeff, W. : Ueber die Centrosome in den spermatogenen Zellen. Ber. d. Deutsch. Bot, 
Gesellsch., Bd. xvii, pp. 199-204. 1899. 
Chamberlain, Chas. J. : Mitosis in Pellia. Bot. Gaz., vol. xxxvi,pp. 28-50. 1903. 
Davis, Bradley Moore : Nuclear Studies on Pellia. Ann. of Bot., vol. xv, pp. 147-80. 1901. 
Farmer, J. BreTland : On Spore Formation and Nuclear Division in the Hepaticae. Ann, 
of Bot., vol. ix, pp. 469-521. 1895. 
--- and Reeves, Jesse : On the Occurrence of Centrospheres in Pellia 
epiphylla , Nees. Ann. of Bot., vol. viii, pp. 219-24. 1894. 
•-—-■ - and Williams, J. Ll. : On Fertilization and the Segmentation of the 
Spore in Fucus. Proc. Roy. Soc., London, vol. lx, pp. 188-95. 1 896-7. 
---: Contributions to our Knowledge of the Fu* 
caceae : their Life-history and Cytology. Phil. Trans. Roy. Soc., London, vol. cxc, 
series B, 1898. 
Gregoire, Victor, et Berghs, Jules: La figure achromatique dans le Pellia epiphylla. La 
Cellule, tom, xxi, i er fasc. 1904. 
