58 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
BOTANY. 
A. GENERAL, including* the Anatomy and Physiology 
of the Phanerogamia. 
a. Anatomy. 
(1) Cell-structure and Protoplasm. 
Absorption of Solid Substances by Protoplasm, and Formation of 
Vacuoles.* — Prof. W. Pfeifer has made a series of observations on the 
mode in which solid substances are absorbed by living protoplasm, the 
object of examination being chiefly plasmodes of Chondrioderma dijforme. 
He believes that the absorption cannot be the result of chemical irritation 
nor of sensibility to contact, but of a purely mechanical force, whether 
from the weight of the substances absorbed, or from the resistance which 
they offer to the movements of the arms of the plasmode. Passing 
through the hyaloplasm, these substances are often taken up by vacuoles, 
though this is not always the case. After a certain period they are again 
expelled from the plasmode, but only while it is in motion and under- 
going changes of form. Absorption of solid substances by protoplasm 
inclosed in a cell- wall was also observed. 
Pfeffer contests the view of de Vries and Wentf that all vacuoles 
must necessarily result from the division of vacuoles already in exist- 
ence. He was able, by placing the plasmode in a saturated solution of 
a substance which is not too soluble and at the same time is not in- 
jurious, to produce in the hyaloplasm artificial vacuoles with all the 
properties of natural vacuoles. He found in these plasmodes no sharp 
distinction between hyaloplasm and granular protoplasm, the latter being 
simply the former rendered turbid by imbedded substances. The 
artificial vacuoles may even possess slight powers of pulsation. 
With regard to the consistency of protoplasm, the author asserts that 
bodies composed of naked protoplasm, and especially the vibratile cilia 
of swarm-cells and of antherozoids, have a greater power of cohesion 
than protoplasm inclosed in a cell-wall. With regard to the cause of 
movements of irritability, such as those of the stamens of Cynaraceae, he 
combats the theory of Vines and Gardiner, that it is due to an active 
contractility of the protoplasm, since, in such cases at all events, the 
protoplasm does not possess a sufficient degree of cohesion. The cause 
of the movements must be sought for either in an osmotic elimination 
of substance, or in a diminution of turgidity. 
The author states that certain substances diffuse rapidly through the 
cytoplasm, while they pass only comparatively slowly through the mem- 
brane of the vacuoles ; this difference demonstrates, in his opinion, the 
presence of continuous protoplasmic membranes which determine the 
osmotic absorption of substances by the protoplasm. 
Cell-division in Spirogyra.ij: — M. C. Degagny has adopted a new 
method of observing cell-division in Spirogyra orthospira, from which he 
has obtained interesting results. He exposes the filaments for some 
* Abhandl. Sachs. Gesell. Wiss., xvi. (1890) pp. 149-315. See Bot. Centralbl., 
xliv. (1890) p. 180. 
f Cf. this Journal, 1888, p. 981. J Comptes Rendus, cxi. (1890) pp. 282-4. 
