360 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
of facts opposed to it. He finds that in Hydrodictyon utriculatum there 
is uo simultaneous division of the protoplasts into zoospores, but that 
the first process is a peculiar breaking-up of the parietal layer of proto- 
plasm into ribbon-shaped pieces, from the division of which the zoospores 
are formed. In this alga, as in Botrydium granulatum , the original 
vacuole of the mother-cell remains until the zoospores are mature, and 
there is no evidence of its breaking up into from 7000 to 20,000 small 
vacuoles, corresponding to the number of the zoospores. Elebs further 
points out that Went fails to indicate any method by which pathological 
can be distinguished from normal vacuoles. 
Formation of Cell-wall in Protoplasts not containing a Nucleus.* 
— Herr E. Palla has made further observations which confirm his pre- 
vious statement that it is possible for a cell-wall to be formed round 
protoplasm destitute of a nucleus. One series of experiments was made 
on pollen-grains — Leucojum vernum, Galanthus nivalis , Scilla bifolia , 
Hyacinthus orientalis , and others — causing them to germinate in a solu- 
tion of sugar and gelatin, by which the extremity of the pollen-tube was 
ruptured, and both nuclei expelled. Although the part below usually 
perished, yet in many cases a fresh cap of cellulose was formed on the 
apical side. Similar results were obtained, by the process of plasmo- 
lysis with a 10 per cent, solution of sugar, with leaves of Elodea 
canadensis , root-hairs of Sinapis alba, rhizoids of hlarchantia polymorpha , 
and filaments of (Edogonium . The author does not reject the hypothesis 
that the formation of cellulose in such cases may be a secondary result 
of the activity of the nucleus which was once present. 
Antagonistic Molecular Forces in the Cell-nucleus.t— M. C. 
Degagnv discusses the question whether the facts already described in 
the division of the cell-nucleus in Spirogyra prove the existence of an 
antagonism between the different chromatic portions of the nucleus. 
The first indication of the rupture of the equilibrium which reigns in 
the interior of the nucleus is its increase in volume ; the nucleole then 
no longer occupies its central position, but becomes placed sometimes on 
one side, sometimes on the other, of the nucleus ; this may be due to the 
entrance into it of the red granulations ; for, before their appearance, it 
had remained in equilibrium. The separation of the nucleolar particles 
usually takes place slowly, but at other times the nucleole breaks up 
suddenly, and the red particles are projected, not in all directions, but 
all on the same side, and the nucleole itself is then driven in a direction 
opposite to that of the granulations, and a visible antagonism is thus 
manifested between the different portions of the chromatic substance of 
the nucleus. Evidence of a similar nature is presented in the formation 
of the nuclear membrane. 
C 2) Other Cell-contents ('including 1 Secretions). 
Structure and Formation of Chromatophores.* — Herr H. Bredow 
has investigated this subject, chiefly in connection with the development 
and germination of seeds. His observations agree with those of Tschirch, 
* Flora, lxxiii. (1890) pp. 314-31 (1 pi.). Cf. this Journal, 1890, p. 475.) 
t Comptes Rendus, cxi. (1890) pp. 761-3. Cf. this Journal, ante , p. 58. 
t Jahrb. f. Wiss. Bot. (Pringsheimj, xxii. (1890) pp. 349-414. 
