348 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Suberous Layer and Suberin.* * * § — M. C. van Wisselingb gives the 
result of a series of chemical experiments on the nature of the corky 
layer in trees, those especially examined being Quercus suber, Cytisus 
Laburnum, Virgilia lutea, Ilex Aquifolium, Betula alba, Pyrus Malus, and 
Salix caprea. The existence of cellulose in the corky layer was dis- 
proved, no indication could be discovered of the occurrence of this sub- 
stance between the middle lamella and the cellulose-wall, which is 
generally more or less lignified. The corpuscles described by Wiesner 
under the name of dermatosomes are united with one another, not by 
protoplasm, but by a totally different substance. The number of 
substances which produce cork is probably much larger than is generally 
supposed. 
Mucilage-threads in the Intercellular Spaces of the Roots of 
Orchidese.f — In the intercellular system of the roots of several species 
of Lpipactis and Cephalanthera, Herr F. Noack finds branched or 
moniliform threads or “ tendrils ” of mucilage springing from the cell- 
walls, which might easily be mistaken for the mycele of a parasitic 
fungus. Similar structures have been found in the spongy parenchyme 
of the leaves in Marattiacese, and in the spongy parenchyme of the aerial 
roots of Phoenix spinosa. In the Orchidese they occur only in the 
cortical parenchyme of the roots ; and their distribution in the inter- 
cellular spaces is very irregular. The chemical reactions show that 
they do not consist of cellulose. The mucilage appears to be not a 
secretion of the cell, but the result of local transformation of the layer 
of cellulose which lies immediately beneath the central lamella. 
Mucilage Receptacles of Hypoxidese4 — Sig. R. Pirotta finds, in 
Hypoxis and other allied genera, receptacles for mucilage which have not 
hitherto been noticed. They occur in the rhizome and in the leaf-stalk 
or leaf-sheath, but not in the root nor in the floral region, nor in the 
lamina of the leaves. The author regards their presence as a useful 
character for distinguishing the Hypoxidese from the Amaryllidaceae. 
rC4) Structure of Organs. 
Colouring-matter of Pollen.§ — According to MM. G. Bertrand and 
G. Poirault, the colour of dry pollen-grains (Urticacese, Gramineas, &c.) 
is due to the cutinization of their outer membrane, while that of moist 
grains is derived from the carotin contained in the oily matter which 
covers the surface of the grains. This oil is coloured an indigo-blue by 
sulphuric acid ; and the authors give the details of micro-chemical ex- 
periments by which they identified its colouring substance with the 
carotin which is widely distributed through the vegetable kingdom. 
They suggest that the purpose served by the carotin may be the 
powerful odour which accompanies its oxidation, and which may attract 
the visiting insects. The plant experimented on was Verbascum thapsi- 
forme . 
* Arch. Neerl. Sci. Ex. et Nat., xxvi. (1893) pp. 305-53. 
f Ber. Deutsch. Bot. Gesell., x. (1893) pp. 645-52 (1 pi.) 
X Atti R. Accad. Lincei, i. (1892) pp. 376-8. 
§ Coraptes Rendus, cxv. (1892) pp. 828-30. 
