ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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are not, as a rule, found in tlie earliest stages of the development of the 
organ, and are evidently formed by transformation from leucites. They 
arc often surrounded by a membrane, and are always imbedded in the 
parenchyme, and surrounded by ordinary cells. 
Dimorphic Branches of Castilloa.* * * § — M. F. A. F. C. Went describes 
the peculiar habits of Castilloa elastica , a native of Java, belonging to 
the Urticaceae, of producing, in addition to the ordinary branches, others 
which are cast off. These branches differ from the ordinary ones in 
their phyllotaxis, and bear no leaf-buds, although they may produce 
inflorescences in their leaf-axils. When the deciduous branches are 
thrown off, they leave a hollow in the stem. The purpose of the 
arrangement appears to be that the tree may form a crown of leaves at 
the summit of the stem. 
Scales of the Bulbs of Allium.f — Dr. I. Baldrati discusses the 
morphological character of the hard scales found in the bulbs of certain 
species of Allium ( [neajpolitanum , Chamsemoly , roseum ), and determines 
them to be of an essentially foliar nature. They are always provided 
with a sclerotic stratum, and appear to serve a protective purpose to the 
remainder of the bulb. In A. nigrum all the stages of transformation 
can be followed, from the ordinary leaves to these fleshy structures, the 
green tissue being the first to disappear. 
Underground Runners.^; — From observations made chiefly on Enj - 
tlironium americanum and Arissema tripliyllum , Miss Ida A. Keller con- 
cludes that the production of underground runners or stolons in plants 
which possess these organs is in inverse proportion to the energy ex- 
pended in the production of fruit and seeds. 
Contractile Roots of Arum.§ — Herr A. Rimbach describes the con- 
tractile roots which appear on the two-year-old rhizomes of Arum 
maculatum. The contractility is confined to the basal portion of the 
root, and may amount to as much as 50 per cent, of the length of this 
portion. The tendency is to drag the growing point further and further 
below the surface. A contraction to the extent of 18 mm. was measured 
on one root. On a mature rhizome only about one-half of the roots are 
contractile, and these are about double the diameter of the non-contractile 
ones. The contractile tissue is the cortical parenchyme ; the central 
vascular cylinder and the outermost part of the cortex remaining 
passive. 
Evolution of the Cyclamen.|| — Mr. W. T. Thiselton-Dyer traces 
the development under culture of the various varieties of the Cyclamen 
from C.persicum ; the most remarkable forms consisting in the fimbriation 
of the petals and in the appearance of a plumose crest on each petal. 
The author regards the general tendency of a plant varying freely under 
artificial conditions to be atavistic, i.e. to shed adaptive modifications 
which have ceased to be useful, reverting to a more general type. 
* Ann. Jard. Bot. Buiteuzorg, xiv. (1896) pp. 1-16 (3 pis.). 
t Nuov. Giorn. Bot. Ital., iv. (1897) pp. 214-23 (1 pi.). 
X Proc. Acad. Nat. Sci. Philadelphia, 1897, pp. 161-5 (1 pi.). 
§ Ber. Deutsch. Bot. Gesell., xv. (1897) pp. 178-82 (1 pi.). 
11 Proc. Roy. Soc., lxi. (1897) pp. 135-47 (10 figs.) ; Nature, lvi. (1897) pp. 65-8 
(10 figs.). 
