734 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
BOTANY. 
A. GENERAL, including the Anatomy and Physiology 
of the Phanerogamia. 
a. Anatomy. 
C13 Cell-structure and Protoplasm. 
Structure of the Cell.* * * § — Dr. C. Acqua has investigated some 
points connected with the growth of the vegetable cell, in the case of 
germinating pollen-grains (hyacinth, Eschscholtzia californica , Olivia). 
His observations led him to the conclusion that the new cell-walls 
are a direct product of the activity of the peripheral layer of proto- 
plasm. In consequence of the rupture of the cell-wall, a portion of the 
protoplasm is forced out, and the portion that still remains inside 
breaks up into masses united by delicate protoplasmic filaments, which, 
after a time, become transformed into threads of cellulose. The 
increase in superficies was seen in many cases to take place by the 
distension and subsequent laceration of the old layers, while new layers 
become formed within, which, continuing to grow, are in their turn dis- 
tended and lacerated. The increase in length of the pollen-tubes is 
entirely apical. 'When this growth takes place without interruption, 
the distension and formation of fresh cellulose may take place without 
any laceration. 
As regards the part played by the nucleus, the author comes to the 
same conclusion as Palla,j that masses of protoplasm without any 
nucleus may form a new cell-wall. He was also able to demonstrate 
the possibility of maintaining the vitality of the nucleus for some days 
when entirely removed from the cell and completely isolated from the 
cytoplasm. 
Movements of Protoplasm.! — Ida A. Keller maintains that the cur- 
rents of protoplasm so often observed in plants are not a normal pheno- 
menon, but are a symptom of approaching death, and the result of 
pathological conditions. They may be caused by injury, by sudden and 
great changes of temperature, by the action of chloroform, by solutions 
of sugar and potassium nitrate, by absence of nitrogen, &c. In Elodea 
canadensis they are ordinarily observed in leaves which are beginning 
to wither, and do not cease until immediately before actual death. The 
author derived the same conclusion from the observation of leaves of 
Trianea bogotensis and Butomus umbellatus, leaf-stalks of Alisma Blantago 
and Umbilicus horizontal is, stems of Tradescantia virginica, air-roots of 
Orchidese, tentacles of Drosera , seedlings of Vida Faba and Brassica 
Napus , and hairs of Tradescantia, Primula chinensis , &c. 
Callose.§ —Under this term M. L. Mangin describes a substance 
which he believes to be an essential constituent of the cell-wall, 
although he has not at present been able to isolate it. 
* Atti R. Accad. Lincei (Rend.), vi. (1890) pp. 577-9. 
f Cf. this Journal, ante , p. 475. 
% ‘ Ueb. Protoplasma-Stromung im Pflanzenreich,’ Zurich, 1890, 47 pp. See Bot. 
Centralbl., xliii. (1890) p. 196. 
§ Comptes Rendus, cx. (1890) pp. 644-7. Cf. this Journal, 18S9, p. 538. 
