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1910] CURRENT LITERATURE 77 
them to discover if these bunches might correspond in any way with the “root 
tubercles” of recent plants. As only one such case has been recorded from the 
Coal Measures, the result is of special interest. These lateral roots are found 
to have a thick cortex divisible into two regions, the inner of which contains dark 
cells that show evident fungal hyphae. The fungus occurs in knots of non- 
septate hyphae that bear sometimes terminal vesicles, but there was no trace of 
any spore-formation. The conclusion is reached that ‘‘Cordaites was probably 
a tree inhabiting saline swamps, and having bunches of coralline rootlets on its 
roots, such as are known to occur in many recent plants growing under similar 
conditions.””—J. M.C. : 
Anatomy of Equisetum.—Eamrs°° has discovered that although the xylem 
of Equisetum is centrifugal throughout the vegetative stem, it is also centripetal 
in the axial bundles of the strobilus and of the sporophylls; in the former the 
bundles are “‘weakly mesarch,” in the latter “strongly so.” This suggests that 
the most primitive representatives of Equisetales had well-developed centripetal 
wood, and connects them with such ancient forms as Sphenophyllales, already 
Suggested by Scort’s discovery of centripetal wood in a calamite. All the large 
groups of pteridophytes are now known to possess centripetal wood, so that “such 
bundles in higher plants can be of no other phylogenetic value than as indicating 
general cryptogamic affinities.” At the same time, Equisetum confirms the value 
of the leaf gap as a phylogenetic character, since in no case does the passage ofa . 
leaf trace from the stele leave a gap.—J. M. 
Protection against light.—Mar.orH describes some very remarkable ways 
in which a few African desert plants reduce the amount of light which the 
green tissues of their leaves receive.3?7 He refers to three categories: (1) plants 
with fleshy and green leaves, having membranous stipules which extend beyond 
and conceal them; (2) plants with fleshy and green leaves, without stipules, but 
invested by the dried-up remnants of the older leaves; (3) plants with windowed 
faves. This most curious arrangement is characteristic of plants with very fleshy 
leaves whose blunt, plane, or erose tips alone reach the surface of the soil, the body 
of the leaf being completely buried. This exposed tip lacks chlorophyll, and 
through this as through a window the light reaches the green tissue, which is 
restricted to the sides of the fat leaf. Several species of Mesembryanthemum 
have this peculiarity.—C. R. B. 
“ Transpiration ” in aquatics.—Under a similar misleading title THopay and 
SYKrs38 present a brief account of a few experiments that show movement of 
Sain 
3° Eames, Arruur J., On the occurrence of centripetal xylem in Equisetum. 
Annals of Botany 23:587-6or. pl. 45. 1909. 
37 Martotu, R., Die Schutzmittel der Pflanzen gegen tibermissige Insolation. 
Ber. Deutsch. Bot. Gesells. 2'7: 362-371. figs. 2. 1909. 
38 THopay, D., anp SyKEs, M. G., Preliminary observations on the transpiration 
current in submerged water-plants. Annals of Botany 23:635-637- 1909 
