360 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Plasomes.* * * § — Mr. A. Schneider confirms the observation of Wiesner 
with respect to the occurrence of plasomes in the living cell, in the case of 
the palisade-cells in the root-tubercles of Cycas revoluta. These plasomes 
were capable of being introduced into other cells by inoculation. They 
develope into dermatosomes outside the living cell, although they do 
not divide under these circumstances. As soon as all plasomes capable of 
growth have reached maturity, apparent reproduction ceases. Further 
illustrations were afforded by the tuber of the potato and the root of 
maize. 
Nucleoles and Centrosomes in Psilotum.f — Herr G. Karsten calls 
attention to the behaviour of the nucleoles during the division of the 
nucleus in the sporanges of Psilotum triquetrum. They occur both in 
the tapetal cells and in the sporogenous tissue, having a more elongated 
shape in the former, more spherical in the latter. In the resting condition 
of the nucleus these nucleoles always occupy a peripheral situation ; 
shortly before division takes place they emerge from the accompanying 
chromosomes into the surrounding protoplasm, assuming the form of 
sharply defined red-stained spheres. The number of nucleoles which 
emerge is very rarely more than two, one from each side of the nucleus. 
These appear to be the points at which the separating elements of the 
nucleus are formed. They move each to one pole of the nuclear spindle, 
and there divide at the time when the chromosomes break up into two 
longitudinal halves. From the time of their entrance into the proto- 
plasm they behave precisely in the same way as centrosomes ; the author 
proposes for them the term “ nucleo-centrosomes.” He thinks that they 
are, in all probability, identical with the bodies described by Strasburger 
as being thrown off in the division of the nucleus, which he terms 
secretion-bodies. 
Formation of Cell-walls.J — M. E. de Wildeman contests Zimmer- 
mann’s theory of the mode of formation of septa in cells, and maintains 
that the membranes are at first semi-fluid, but rapidly become solid. 
Waviness of the Cell-wall of the Exoderm of Roots.§ — Herr A. 
Eimpach finds that the radial cell-walls of the exoderm of roots are, in 
both Monocotyledons and Dicotyledons, frequently wavy in a similar 
way to those of the endoderm, though in a slightly different manner, 
which is described in detail. The author has proved by experiment that 
this waviness is caused, not by any peculiarity in the internal structure 
of the cell-wall, but by the contraction of the root, as is also the case 
with the endoderm. 
(2) Other Cell-contents (including- Secretions}. 
Enzymes.]] — Sigg. C. Fermi and L. Pernossi record the results of 
their observations on the action of enzymes under various conditions. 
Most of the experiments were made with pepsin and trypsin, though 
* Bull. Torrey Bot. Club, xx. (1893) pp. 379-83. 
f Ber. Deutsch. Bot. Gesell., xi. (1893) pp. 555-62 (1 pi.). 
X Atti Congr. Bot. Internaz. Genova, 1892 (1893) pp. 508-13. See Bot. Cen- 
tralbl., lvii. (1894) p. 209. 
§ Ber. Deutsch. Bot. Gesell., xi. (1893) pp. 467-72. Cf. this Journal, 1893, 
p. 652. (I Centralbl. f. Bakteriol. u. Parasitenk., xv. (1894) pp. 229-34. 
