618 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Processes of Growth in the Vegetable Cell.* — Herr J. Behrens has 
investigated the phenomena connected with the formation of so-called 
cellulose-folds, chiefly in certain species of Spirogyra, and in the assimi- 
lating cells of Pinus. In Spirogyra Weberi the splitting up of the 
nucleus into two is readily followed. The earlier processes resemble 
those of direct division ; but fixed preparations show that the entire 
process of nuclear division is the ordinary one of karyokinesis. The 
space between the combined threads of the daughter-nuclei is a vacuole. 
In this, as in other examples which are described (epidermal cells of 
Tradescantia , &c.), no entrance of cytoplasm into the nucleus could be 
detected. The vacuole between the nuclei in Spirogyra is not formed 
by the enlargement of one previously in existence, but is altogether 
freshly formed ; ultimately it entirely disappears. 
The peculiar formations on the septa of Spirogyra Weberi have been 
hitherto regarded as folds ; but the author confirms the statement of 
Strasburger that they are thickening-bands ; they grow by apposition 
at their margin, like the septa themselves. The similar folds in the 
cell-walls of the assimilating tissue in the leaves of Pinus sylvestris can 
also, according to the observations of the author, be explained on the 
theory of apposition, though it is not impossible that intussusception 
may also contribute to their growth. The processes appear to be similar 
in the folds of the cell-wall in the mesophyll of Galamagrostis epigejos , 
and in those of the shields of the antherid of Chara foetida. 
Commenting on this paper, Herr G. Haberlandt j points out that his 
views on the position of the nucleus in mature cells, J which Behrens 
has criticized unfavourably, refer simply to the fact that the nucleus does 
take up a definite position in such cells, and do not touch the question 
whether this is brought about by an active motion in the nucleus 
itself, or whether it is carried passively by currents in the protoplasm. 
Reactions of Cytoplasm.§— From experiments on the leaves of a 
specimen of Echeveria , Herr T. Bokorny finds that a 1 per cent, solution 
of caffein causes aggregation of the cytoplasm and formation of proteo- 
somes without killing the protoplasm. From the fact that there is 
frequently a very great abundance of both protoplasm and tannin in the 
same cell, he infers a close connection between these two substances. 
Quantitative Estimate of Cellulose. || — By the use of Hoppe- 
Seyler’s method, Herr G. Lange has determined the proportion of 
cellulose in various woods and in turf to vary from 44 per cent, in the 
latter to 55 per cent, in oak-wood. 
Alkalinity of Protoplasm.^ — Herr A. Meyer contests the statement 
of Schwarz** that the protoplasm in the living cell has generally an 
alkaline reaction. He affirms that this reaction is frequently the result 
of the treatment to which the protoplasm has been subjected in making 
the experiments ; and, moreover, that the so-called alkaline reaction of 
* Bot. Ztg., xlviii. (1890) pp. 81-8, 97-101, 113-7, 129-34, 145-50. 
t T. c., pp. 221-2. X Cf. this Journal, 1887, p. 980. 
§ Ber. Deutsch. Bot. Gesell., viii. (1890) pp. 101-12 (1 pi.). 
|| Zeitschr. f. Physiol. Chemie, xiv. pp. 283-9. See Bot, Centralbl., xlii. (1890) 
p. 307. 
IT Bot. Ztg., xlviii. (1890) pp. 231-7. 
** Cf. this Journal, 1887, p. 979. 
