214 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
BOTANY. 
A. GENERAL, including the Anatomy and Physiology 
of the Phanerogamia. 
a. Anatomy. 
Cl) Cell-structure and Protoplasm. 
Cell-structure.* — Dr. A. Zimmermann gives a very complete and 
valuable resume of recent observations on the structure of the vegetable 
cell and of vegetable protoplasm. 
In reference to the mode of cell-formation, he alludes to the remark- 
able observations of Mdme. Weber- van-Bosse on the formation of spores 
in a thick peripheral layer within the tubes of Phytophysa Treubii, which 
he considers to correspond very closely with the formation of cells in 
the higher plants. 
With regard to the consistency of protoplasm, the evidence is alto- 
gether in favour of its being more fluid than solid, though it is locally 
denser, especially at its bounding-surfaees, both towards the cell-wall 
and towards the cell-sap. 
On the subject of the finer structure of the protoplasm, the author dis- 
cusses the three principal theories, the filament-theory (including Fayod’s 
theory of spirosparts and spirofibrillse), the honeycomb theory, and the gra- 
nular theory, and gives the arguments for and against each of these views. 
The spiral theory he has not been able to confirm by his own observa- 
tions ; he considers it most probable that vegetable protoplasts always 
have a granular structure. The position of the chromatophores within 
the protoplasts is affected by external factors ; and it is probable also 
that the position of other substances enclosed within the cytoplasm is 
due to other causes than structural differences. 
Under the head of the chemical composition of the protoplast, the 
existence of nuclein and nucleinic acid is discussed, as is Loew and 
Bokorny’s theory of the aldehyd nature of living protoplasm. A full 
account is given of the various instances in which protoplasmic connec- 
tions from cell to cell have been detected, and of the views with regard 
to their function. The composition and finer structure of the resting 
nucleus are then treated of, with especial reference to (1) the chromatic 
(cyanophilous) constituents of the nucleus or nuclear framework, (2) the 
nucleoles or erythrophilous constituents of the nucleus, (3) the nuclear 
membrane, (4) the nuclear sap, (5) protein-crystalloids. The next sub- 
jects are the centrosomes or attraction-spheres, all the various observations 
on these structures being referred to, and the division of the nucleus. 
A separate section is then devoted to the special behaviour of the 
nucleus in the different groups of plants, viz. in the Algae (including 
diatoms, Cyanophyceae, bacteria, and Characese), Fungi (including 
Myxomycetes), Bryophytes, Pteridophytes, Gymnosperms, and Angio- 
sperms. 
Under each heading there is a copious citation of literature down to 
the year 1893. 
* Bot. Centralbl., 1893, Beih., pp. 206-17, 321-51, 401-36 (6 figs.). 
