ZOOLOGY AND BOTANY, MICROSCOPY, ETC, 
305 
teristics of the two modes of deposition of silica, which he terms 
t: Kieselkorper ” and “ Kieselfiillungen.” The latter agree in character 
with the peculiar “ tabaschir ” of the Bambusese. 
Structure of Diapensacese.* * * § — Herr W. Grevel describes the anato- 
mical and histological structure of several species belonging to this order 
of Ericales. Among the general characteristics of the order is the entire 
absence of secondary medullary rays in the stem. The primary vessels 
have, as a rule, but slightly thickened walls. The epidermal cells of 
the leaves- have always wavy walls. The elements of the xylem, except 
the primary annular vessels, have, for the most part, bordered pits. No 
mycorhiza could be detected in the roots. The points of resemblance 
and difference with the allied orders of Ericales are pointed out. 
Anatomy of Cissus gongylodes.f — M. H. Jumelle describes in detail 
the structure of this remarkable climber from Brazil, belonging to the 
Ampelidese, of which the most striking characters are the broad winged 
stem, the red aerial roots springing from the nodes, and the tubercles 
formed at the ends of the branches, which become detached and serve to 
propagate the plant. These tubercles are modified internodes, in which 
are stored up large quantities of food-materials, especially starch and 
mucilage, The aerial roots, if uninjured, remain unbranched until they 
reach the soil, when they branch copiously. The exposure to the air has 
a tendency to increase the thickness of the central cylinder, with an 
increase of the size of the pith and of the medullary rays. In the light 
there is a large formation of calcium oxalate. 
(4) Structure of Organs. 
Influence of the Soil on the Colour of Flowers.^ — Herr H. Molisch 
has experimented on the influence of the chemical composition of the 
soil in changing the natural pink colour of the flowers of Hydrangea 
liortensis to blue. He finds that this change is invariably brought about 
by the presence of alum in the soil, and that the efficient constituent in 
the alum is aluminium sulphate, which has the same effect as alum. 
Ferric sulphate has a similar effect ; while the result with other salts of 
iron was mostly negative. The blue colour is due to a chemical combi- 
nation of the salts in question with the anthocyan, which is the cause of 
the natural red colour of the flowers. The most sensitive part of the 
flower to the change in colour is the filament. 
Homology of the AntherJ — According to M. D. Clos, the filament 
of the stamen only very rarely represents the petiole of a leaf. In 
most Apopetalie it corresponds to a linear petal, to the median vein r 
to a narrow longitudinal band of a broad sessile petal (Ranunculaceae, 
Berberidese), or to the claw of an unguiculate petal (Sileneae, many Cru- 
ciferae). In the Apopetalte with polyadelphous stamens the staminal 
vessels are very frequently analogous to the veins of the petals, the 
number of these very often corresponding to that of the staminal 
phalanges. The anther, whether sessile, dorsifixed, or basifixed, is a 
* Bot. Centralbl., Ixix. (1897) pp. 257-67, 309-15, 312-7, 369-77, 401-11^(1 pi.). 
t Rev. Gen. de Bot. (Bonnier), ix. (1897) pp. 129-19 (8 figs.). 
X Bot. Ztg., lv. (1897) l te Abt., pp. 49-61. 
§ Comptes Rendus, exxiv. (1897) pp. 808-10. 
