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SUMMARY OF CURRENT RESEARCHES RELATING TO 
superficial in tlie species which inhabit dry, depressed in the tissue 
of those which inhabit boggy situations. In C. arenaria and other 
species with a similar habit, the mechanical elements are but feebly 
developed in the root ; while in the aquatic species we find a strongly 
developed peripheral ring of sclerenchyme, and a thick- walled endoderm 
usually consisting of three or four rows of cells. 
Anatomy of the Tubiflorse.* — Herr G. von Sclilepegrell describes in 
great detail the comparative anatomy of the natural orders belonging to 
the Tubiflorae, comprising the Hydrophyllaceae, Borragineas, Polemo- 
niaceae, Solanaceae, Nolanaceae, and Convolvulaceae, especially with a view 
to the classification of the genera. 
The Hydrophyllaceae are divided into the Hydrophylleae, in which 
the vascular bundles are isolated, and are surrounded within and 
without by thick-walled unlignified tissue ; and the Phacelieae, Nameae, 
and Hydroleae, which have the vascular bundles arranged in a closed 
ring ; the last tribe is provided with large air-canals in the cortical 
tissue, which are wanting in the first two. The genera of Polemo- 
niaceae are classified according as the secondary vessels are large ( Cobsea ), 
or small ; in the latter case all the vessels are either collected into 
groups ( Bonplandia ), or dispersed through the xylem (Phlox, Collo- 
mia, Gilia, Polemonium, Loeselia, and Cantuci). The Borragineae are 
divided into two principal groups ; in the Borrageae there are no outer 
bast fibres ; in the Cordieae, Ehretieae, and Heliotropieae, the outer 
bast-fibres form a more or less distinct ring. In the Convolvulaceae 
the anatomical structure is not of itself sufficient to establish a satis- 
factory classification of the genera. In the Nolanaceae the bast -fibres 
form radial rows in Alona and Nolana , but not in Dolia and Bargemontia. 
Among the Solanaceae, there is no inner phloem in Retzia and Loncho - 
stoma , while there is in the other genera of the order, which may be 
distinguished from one another by the nature of the hairs. 
Of the genera the position of which is doubtful according to Bentham 
and Hooker, Amerina is referred to Verbenaceae, Pseudopyxis to Rubiaceae, 
Sclerophylax and Calihrachoa to Solanaceae, Heteranthia and Leucophyllum 
to Scrophulariaceae, Dorsena to Myrsinaceae, Isanthera to Gesneraceae. 
Anatomy of Eriocaulacese.f — From an examination of three genera 
and fifteen species of Eriocaulaceae, Herr Y. A. Poulsen regards them, from 
an anatomical point of view, as typical Monocotyledons. The fissure of 
the stomates is exceedingly narrow, but in other respects they resemble 
those of Gramineae and Cyperaceae. The fibrovascular bundles represent 
a special type, which the author calls “ biconcentric.” Round the axial 
hadrome-bundle is a layer of leptome, which is again inclosed by a 
hadrome-layer. 
Influence of Traction on the Firmness of Plants.]: — Prof. W. Pfeffer 
describes a series of experiments made by R. Hegler on the increased 
strength and development of the mechanical tissues of plants resulting 
* Bot. Centralbl., xlix. (1892) pp. 193-200, 225-31, 257-63, 289-99, 353-60, 
385-93 ; L (1892) pp. 1-7, 33-9 (4 pis.). 
f ‘Anat. Unters. lib. d. Eriocaulaceae,’ 166 pp. and 7 pis., Copenhagen, 1888. 
See Bot. Centralbl., 1892, Beih., p. 34. 
X Ber. Verhandl. K. Sachs. Gesell. Wiss., v. (1892) pp. 638-43. 
