538 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
pockets formed at tlie expense of tlie radical phelloderm ; the presence 
of a metaxylem in the radical stele, &c. The structure is compared 
with that of the allied orders Phryniaceae, Stilboideae, Chloanthoideae, 
and Brunoniaceae. 
(4) Structure of Organs. 
Variation.* — Dr. W. Haacke has made a detailed study of the 
variations, especially numerical, exhibited by Campanula glomerata and 
Tanacetum corymbosum, and points out the general occurrence of what he 
interprets as correlate variations, or of what are certainly simultaneous 
variations in different parts of the plant. He regards cross-fertilisation 
as having the great end of restoring the equilibrium which the individual 
tends to lose. The variations tabulated are interpreted as due to varying 
nutritive conditions in the different localities. 
Mechanics of the Dehiscence of Anthers and Sporanges.j — Con- 
tinuing his researches on this subject, Herr C. Steinbrinck states that 
in the dehiscence of anthers no dynamic function is performed by the 
epiderm, nor by the outer wall of the fibrous layer ; the seat of the 
process lies entirely in the radial walls and the inner tangential walls of 
the fibrous layer. 
In the sporange of Equiselum, on the other hand, the spiral cells of 
the epiderm constitute the mechanically active tissue. In the sporange 
of Ferns the micellar structure of the walls of the cells of the annulus 
is of great importance in the hygroscopic phenomena connected with 
their dehiscence. 
Cones of Coniferae.J — According to Dr. C. v. Tubeuf the statement 
that the scales of the cones of Coniferae, when closed after flowering, 
have their margins firmly attached to one another by thick- walled 
papilla, is true of the Cupressincae only, and not even of all members of 
that tribe. In the Abietineae, the closing is effected in other ways. 
Structure of Aquatic Plants.§ — After a minute description of the 
structure and mode of development of Zannichellia palustris , in which 
he calls attention to the tendril-like nature of the roots, M. G. Hochreu- 
tiner describes the adaptations to their condition of the aquatic plants 
of the Rhone and the Lake of Geneva. The absorption of water and 
of soluble salts takes place in the same way as in terrestrial plants, and 
is greatly promoted by the large intercellular spaces. Transpiration or 
exudation takes place even under water. The stems display, in general, 
a well-marked negative geotropism, due to a sensitiveness not specially 
localised, but distributed through the tissue. The existence of hydro- 
tropism is very difficult to determine in aquatic plants ; but they 
certainly display rheotropism, and in some cases a distinct positive 
heliotropism. 
Oak-leaved Hornbeam.]| — Herr C. Wehmer traces a connection 
between the so-called “ oak-leaves ” of Carpinus Betulus, i.e. leaves differ- 
* Biol. Centralbl., xvi. (1896) pp. 481-97, 529-47. 
f Bot. Jaarb. Gent, vii. (1895) pp. 222-356. See Bot. Centralbl., lvi. (1896) 
p. 402. t Flora, lxxxii. (1896) pp. 75-6. 
§ Rev. Gen. de Bot. (Bonnier), viii. (1896) pp. 90-110, 15S-67, 188-200, 249-65 
(1 pi. and 42 figs.). Cf. this Journal, 1892, p. 63. 
[] Bot. Ztg., liv. (1896) l te Abt., pp. 81-96 (1 pi.). 
