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SUMMARY OF CURRENT RESEARCHES RELATING TO 
is much less developed, and has thinner walls. In the leaf, either the 
epidermal cells only increase in size, or the hypertrophy extends also to 
the other tissues. 
Epitrophy of the Cortex.* * * § — Prof. J. Wiesner states that the 
increased development of cortex on the upper surface of branches which 
are placed obliquely to the horizon is not an isolated phenomenon, but 
is a general characteristic of the Tiliacese and Anonaceae in the tropics. 
(4) Structure of Organs. 
Metamorphosis of Organs. | — Herr A. Mann distinguishes between 
“ ideal ” metamorphosis, when, at any point of an organism, a different 
organ is formed instead of the normal one, and “ real ” metamorphosis, 
when the early stages of the typical and of the metamorphosed organ are 
the same, but one assumes during growth the form and function of 
the other. The cause of the latter is rather in the internal essence of 
the plant than in external factors. The phenomena of metamorphosis 
are illustrated by the case of the metamorphosis of shoots into tendrils 
(Ampelidese, Passifloracese) and into spines (e. g. Sideroxylon spinosum ) ; 
and of leaves into scales (e. g. Vitis), phyllodes (Acacia), spines (e. g. 
Berber is sinensis), and tendrils (e. g. Pisum sativum). 
Adaptation of Plants to External Conditions.:}: — Dr. K. 0. E. 
Stenstrom discusses in great detail the specialities of structure 
characteristic of plants growing in various climatic conditions, and 
especially the occurrence of a xerophilous structure in certain hydro- 
philous plants. The special characters of alpine plants are stated 
to be : — An increase of the underground and a decrease of the aerial 
system ; strengthening of the mechanical elements ; a diminished surface 
and increased thickness of the leaves ; a stronger development of the 
palisade-parenchyme and of the epiderm ; gelatinisation of the inner 
wall of the epiderm ; and a large storing up of tannin. 
Flower of the Hemp.§ — Sigg. G. Briosi and F. Tognini describe in 
great detail the male and female flowers of Cannabis sativa. The ovule 
they regard, from a morphological point of view, as neither strictly of 
an axile nor of a foliar character, but intermediate between the two. 
The male inflorescence is fundamentally a compound raceme, the 
secondary axes of which display a sympodial dichotomy. 
Fossil Pollen.|] — M. B. Renault describes the remarkable structure 
of the pollen-grains in the male fructification of Doleropliyllum, a fossil 
genus from the upper Carboniferous. The intine is pluricellular, com- 
posed of from eight to ten cells. The extine is thick and coriaceous, 
and is furnished with two furrows near together on one side of the grain. 
The portion of the extine between these furrows seems to be lifted off 
in the form of an opercule, through which the intine appears to project 
in its entirety. 
* Ber. Deutsch. Bot. Gesell., xii. (1894) Gen.-Vers.-Heft, pp. 93-6. Cf. this 
Journal, 1893, p. 354. 
t ‘ Was bedeutet Metamorphose in d. Bot.? ’ Miinchen, 1894, 40 pp. and 25 figs. 
X Flora, lxxx. (1895) pp. 117-240 (2 figs.). 
§ Atti 1st. Bot. R. Univ. Pavia, iii. (1894) 119 pp. aud 19 pis. See Bot. Cen- 
tralbl., lxi. (1895) p. 265. || Comptes Rendus, cxix. (1894) pp. 1239-41. 
