620 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
and the fusiform cells in the wood. The distinction is, he states, 
supported neither by the history of their development nor by any 
difference in their structure. 
The resin-passages (in Pinns Strobus) may be divided into two kinds 
— the large passages situated in the inner layers of the cortex, and the 
smaller passages situated nearer the periphery. The former kind 
traverse the branch from its base to its apex, and are in uninterrupted 
communication with those of the previous year. 
Anatomy of Ipomaea versicolor.* — Dr. D. H. Scott finds the follow- 
ing peculiarities of structure in the twining stem of this plant, belonging 
to the Convolvulaceae : — It possesses the bicollateral structure of the 
vascular bundles, which is very characteristic of the order ; but, while 
the structure of the greater part of both stem and root is normal, the 
transitional region between the two presents singular abnormalities. 
The internal phloem extends downwards into the hypocotyl, and passes 
out between the converging protoxylem-groups of each cotyledonary 
pair of bundles, thus joining the external phloem of the root. The 
hypocotyl and adjacent parts of the stem and root have a complex 
secondary wood containing numerous strands of interxylary phloem 
(phloem-islands) imbedded in parenchyme, and produced centrifugally 
by the cambium. 
(4) Structure of Organs. 
Changes in the Form of Plants produced by Moisture and Etio- 
lation. f — Herr J. Wiesner has investigated the changes produced in 
those plants which bear a rosette of ground-leaves, but no stem-leaves, 
by growing either in an atmosphere saturated with moisture or in 
darkness, and finds that they can be arranged in the four following 
categories : — (1) Those which, both in a saturated atmosphere and in 
the dark, lose their radical rosette and form well-developed internodes 
in the stem ( Sempervivum tectorum) ; (2) Those which undergo no 
change under either of these conditions ( Oxalis floribunda, Plantago 
media ) ; (3) Those which form well-developed internodes under the 
influence of darkness, but not under that of saturation ( Taraxacum 
officinale') ; (4) Those which form well-developed internodes under the 
influence of moisture, but not under that of darkness ( Capsella bursa- 
pastoris). 
Mangrove-vegetation4 — Herr G. Karsten enters into further details 
respecting the structure of the Ehizophoreae and other trees which 
compose the mangrove-vegetation of the swamps of the Malayan Archi- 
pelago. In his observations on the structure of the embryo-sac and the 
development of the embryo, he agrees, in all essential points, with 
Treub.§ In all cases, except Lumnitzera and Sonneratia , the embryo-sac 
breaks through the nucellus, usually consumes it, and hence lies free in 
the integument. Typical formation of endosperm occurs in Scyphiphoi’a 
and Nipa. In sheltered situations many mangrove-trees are “ vivi- 
* Ann. of Bot., v. (1891) pp. 173-9 (2 pis.). 
t Ber. Deutsch. Bot. GeseU., ix. (1891) pp. 46-53. 
X Biblioth. Bot. (Luerssen u. Haenlein), Heft 22, 1891 (71 pp. and 11 pis.). Cf. 
this Journal, ante , p. 365. § Cf. this Journal, 1885, p. 271. 
