ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
403 
BOTANY. 
A. GENERAL, including the Anatomy and Physiology 
of the Phanerogamia. 
a. Anatomy. 
(1) Cell-Structure and Protoplasm. 
Idea of the Cell in Botany.* * * § — Herr A. Hansen gives a critical 
review of the various theories with regard to the structure of the cell, 
especially in botany, from the time of Hooke (1667) to that of Sachs, 
criticising adversely the definitions of a cell and of an energid pro- 
posed by the latter authority. | Hansen proposes, for the living cell- 
contents, the new terra biophore. A biophore is an independent trans- 
mitter ( Tr tiger ) of all those forces which are included under the term 
vital phenomena. It consists of a protoplasm-body without nucleus, 
or with one or more nuclei. When enclosed in a membrane, it is termed 
a cell. 
Phenomena of Nuclear and Cell-division. :J — Dr. B. Nemec further 
illustrates his view as to the difference in the prophases of nuclear 
division between the vegetative and the reproductive tissues in the non- 
sexual generation of vascular plants. In the relatively free-lying cells 
of the sporogenous tissue the achromatic figure is multipolar, often 
originating radially round the nucleus ; while in the vegetative tissue 
the achromatic figure is from the first bipolar, and forms a hyaline 
structure surrounding the nucleus. This bipolarity was found in repre- 
sentatives of almost all classes of vascular plants. In none of these 
plants is there any differentiated organ representing the centrosome* 
In all of them the primordium of the achromatic spindle makes its 
appearance as a hyaline structure surrounding the nucleus, forming a 
kind of cap at the pole, to which structure the author gives the name 
of periplast. It possesses the properties of a fluid adherent to the 
nuclear membrane. Its ellipsoidal or oval form in vegetative tissues 
must be due to the action of lateral forces. This is shown by the fact 
that the action of chloroform or of plasmolysis restores to this struc- 
ture its original globular form. The author gives detailed reasons for 
not regarding this effect as pathological. 
Karyokinesis in the Root-tips of Allium. — From a detailed study 
of the karyokinetic division of the nucleus in the root-tips of Allium 
Cepa , Dr. B. Nemec § comes to the conclusion that, even in the vegetative 
tissue of the same species, the process may exhibit considerable varia- 
tions ; no general uniform scheme can be laid down for the development 
of the chromosomes, for their form and length, nor for the mode of 
separation of the longitudinal halves ; but the achromatic figure always 
* ‘ Zur Geschichte u. Kritik d. Zellenbegriffes in d. Bot.,’ Giessen, 1897, 58 pp. 
and 1 pi. See Bot. Centralbl., lxxvii. (1899) p. 21. 
f Cf. this Journal, ante, p. 44. 
j Bot. Centralbl., lxxvii. (1899) pp. 241-51 (7 figs.). Cf. this Journal, 1898, 
p. 437. 
§ Jahrb. f. wiss. Bot. (Pringsheim), xxxiii. (1899) pp. 313-36 (1 pi.). Cf. this 
Journal, ante, p. 168. 
