610 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
BOTANY. 
A. GENERAL, including the Anatomy and Physiology 
of the Phanerogamia. 
a. Anatomy. 
(1) Cell-structure and Protoplasm. 
Elementary Organisms of the Cell.* — Continuing his researches on 
the ultimate structure of the vegetable cell, Herr E. Crato classifies its 
constituents into the four following groups : — The lamellar plastin- 
system (protoplasm), including the pliysodes ; the nucleus ; the chromato- 
phores; and the cell- fluid or enchylema. The physodes are vesicular 
structures, having an intimate connection with the plastin, the contents 
of which have a free power of motion within the lamellae. They must 
be regarded not only as transport-organs for plastic building-materials 
and as reservoirs for specialised substances, but also as important chemical 
constituents, being the sole respiring organs. They include by far the 
larger portion of the structures which have been termed microsomes and 
protoplasm-granules. Their envelope consists of portions of the enclos- 
ing lamellae. 
The author then describes in detail the structure of these various 
ingredients in a large number of representatives of different families, 
cryptogamic and phanerogamic. The apical cells of Ghsetopteris plumosa 
are particularly favourable objects for their observation. In Sphacelaria 
the amoeboid motion of the chromatophores is especially noticeable. 
The author regards intramolecular as the primary mode of respiration ; 
it is the property exclusively of living protoplasm. The chromatophores 
appear to have the function of a condensing apparatus, transforming the 
easily decomposed normal carbon dioxide into carbon compounds with 
six atoms of carbon. 
Formation of the Sexual Nuclei in Lilium Martagon. f— In com- 
paring the divisions which take place in the nucleus of the embryo- 
sac and the pollen-mother-cells with those of the vegetative cells in 
Lilium Martagon, Miss E. Sargant states that the nucleus passes 
through four stages, — the resting-stage, synapsis, spirem- stage, and seg- 
mentation. The resting-stage is the same in both descriptions of cells. 
The condition of synapsis is peculiar to the primary embryo-sac nucleus 
and to that of the pollen-mother-cell. Its characteristic features are, 
contraction of the chromatic thread to one side of the nuclear cavity, 
partial solution of the nucleole, and partial disappearance of the nuclear 
membrane. The structure of the spirem- stage in the embryo-sac nucleus 
is very different from that of the vegetative spirem. Segmentation of 
the spirem-ribbon, that is, its division into lengths by transverse fission, 
occurs in every karyokinesis. The characteristic features of the first 
division of the embryo-sac nucleus are: — (1) The long period of growth 
and development before the formation of the spirem-thread, and its divi- 
sion into chromosomes; and (2) certain peculiarities of form which 
* Beitr. z. Biol. d. Pflanzen (Cohn), vii. (1896) pp. 407-535 (4 pis. and 4 figs.). 
Of. this Journal, 1894, p. 359. 
t Ann. Bot., x. (1896) pp. 445-77 (2 pis.). Cf. this Journal, ante, p. 322. 
