90 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
previous to germination, is formed in very small quantities during the 
digestion of the endosperm. 
B. CRYPTOGAMIA. 
Muscinese. 
Spore-Formation and Nuclear Division in the Hepaticae.* — Prof. 
J. B. Farmer gives an account of the details of nuclear division atten- 
dant on spore-formation in eleven genera of Hepaticse, together with 
certain peculiarities observed in the nuclei of the archespore and of the 
germinating spore. He finds that the number of chromosomes in the 
sporophytic nuclei is double that in the gametopliytic nuclei. 
The Hepatic*©, as regards spore-formation, fall into two groups : 
— (1) The Jungermannia series, in which the spore-mother-cell becomes 
tetrahedrally four-lobed before division ; and (2) the Marchantia series, 
in which (with the exception of Targionia ) no such lobing occurs. In 
the Jungermannia group four centrospheres appear on the periphery of 
the nucleus, and effect the formation of a quadripolar spindle, one arm 
of which is protruded into each of the four lobes of the spore-mother- 
cell. This appearance may either be retained through the first mitosis, 
or the spindle-arms may fuse in pairs ; so that during actual division a 
bipolar spindle only is found. The second division is, so far as could 
be decided, similar to the first one, but differences are seen in the 
rapidity with which the two mitoses succeed each other, this being most 
marked in Pallavicinia. 
In the Marchantia series, Fegatella was especially studied. The 
division here is bipolar, but of a peculiar character. The cell-plate of 
the first division persists as a free plate-like body suspended in the 
cytoplasm. It does not reach the walls, and is rotated, during the 
second division, through an angle of 90°. 
The author lays emphasis on the differences, which are obvious, 
between the nuclear divisions of the spore-mother-cells and those of tho 
other nuclei of the same plant, whether belonging to the gametopliytic 
or sporophytic generation. He discusses the function of the centro- 
spheres, which he regards as the expression of mechanical conditions 
operating in the cell, and not as organised or permanent constituents of 
it. In this connection special stress is laid on the difference between 
the Jungermanniem and Marchantiese. The origin of the chromatin in 
the chromosomes, together with the nature and function of the nucleole, 
are also considered. The latter body is regarded as being concerned, 
probably indirectly, with the formation of chromatin (nuclein). Tho 
evidences for this view rest partly on chemical considerations, and partly 
on the mutual relations observed between the chromosomes and the 
nucleole both at the beginning and end of karyokinesis. The author 
advocates the advisability of regarding the facts of karyokinesis from 
a mechanical standpoint. Thus he regards the achromatic spindle, not 
as an organised structure, developed from any special spindle-forming 
body, but as the ex-pression of stresses and strains operating temporarily 
in the protoplasm of the cell. 
* Ann. Bot., ix. (1895) pp. 353-4, 469-523, G6G-8 (3 pis.). Cf. this Journal, 1894, 
p. 4S3. 
