486 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
y. General. 
Special Characters of Plants at high altitudes.* — M. G. Bonnier 
finds that, when plants are cultivated in alpine regions — other conditions 
except those of climate remaining the same — the aerial stems become 
shorter and prostrate ; the flowers more highly coloured ; the leaves 
thicker and of a deeper green ; the protecting tissues of the stem more 
strongly developed ; and, in consequence of the greater development of 
the palisade-tissue and the abundance of chlorophyll, the assimilation 
in the leaves becomes more energetic in proportion to the surface. 
Myrmecophilous Plants.j — Mr. W. Trelease describes the extra- 
floral nectaries for the entertainment of ants in CalycantJms , and for the 
colonies of Aphides in Andromeda. Bitter B. v. Wettstein J gives a 
useful bibliography of the phenomenon of myrmecophilism. 
Herr K. Schumann § treats generally of the structures for the 
accommodation of ants in stems, branches, and leaves ; and describes in 
particular the bladders on the branches of Duroia Jiirsuta, the entrances 
into the tuberous stem of Myrmecodia bullata, the bladders on the under 
side of the leaves of Tococa lancifolia , and on the upper side of the 
leaves of Duroia saccifera , and Muller’s bodies in Cecropia. 
Nanism in the Vegetable Kingdom. || — Dr. D. Clos discusses the 
conditions under which plants exhibit nanism, or the dwarfed con- 
dition, — its causes, whether internal or external, and the various modes 
in which it manifests itself. 
Relationship between Snails and Plants. ^ — Herr F. Ludwig 
describes the mode in which the gigantic leaves of Petasites officinalis 
and those of other plants are destroyed by snails, especially by Succinea 
putris, leaving nothing but a skeleton of vascular bundles. As 
previously described in the case of the hop, the snails appear to have a 
special liking for the patches of parasitic fungi, e. g. Coleosporium Sonchi 
and Puccinia Poarum, which frequently occur on the leaves. 
Use of Micrography in Botany.** — M. P. Vuillemin discusses the 
use of micrographic characters in descriptive botany. He concludes 
that their employment may be recommended from three points of view, 
viz. (1) to determine incomplete plants, or plants altered in their form, 
and species of minute size ; (2) to corroborate or to rectify classifications 
based on other characters ; (3) for the determination of certain questions 
relating to the genetic relationship of plants, which are unapproachable 
by other modes of research. 
* Comptes Rendus, cx. (1890) pp. 368-5. 
f Psyche, 1889, pp. 171-80. See Biol. Centralbl., x. (1889) p. 41. Cf. this 
Journal, ante , p. 212. 
X See t. c., p. 44. § See t. c., p. 45. 
(I Mem. Acad. Sci. Toulouse, 1889, pp. 375-406. 
t SB. Gesell. Naturf. Freunde Berlin, 1889, p. 197. See Bot. Centralbl., xli. 
(1890) p. 295. Cf. this Journal, 1889, p. 548. 
** Bull. Soc. Bot. France, xxxvi. (1889) Actes du Congres de Bot., pp. xc-xcix. 
