1922] ; CURRENT LITERATURE 343 
His preparations of the diseased tissue show fairly large irregularly shaped 
corpuscles and very small granules, both clearly foreign elements, being entirely 
absent in healthy tissue. The author agrees with IwANowsxktas to the probable 
interpretation of the foreign elements, namely, ‘that the minute granules are 
very small bacteria, carriers of the virus, and further that the irregularly shaped 
corpuscles must be considered as a pathological product of reaction of the virus 
carrier on the cell plasm.” This causal organism is thought to be a species of 
Strongyloplasma, and is named S. Iwanowski in honor of its original discoverer. 
Effect of age on plant structure.—Miss TELLEFSEN" has studied the effect 
of age upon certain tissues of Salix nigra. This species was chosen chiefly 
tematic become larger. The average area of vein islets in leaves from older 
trees is smaller than average vein islet areas of leaves from younger trees, the 
amount of vascular tissue increasing with senility, thus reducing the average 
area of vein islets —J. M 
Leaf-skin saci) lied SAUNDERS” has reached the conclusion that the 
surface tissue of the seed plant shoot is of foliar origin, meaning that the leaves 
are decurrent, not merely those that are usually called so, but all leaves. In 
the same way the superficial tissue of the hypocotyl are derived from the cotyle- 
dons. This so-called leaf-skin is formed by the “downward growth and exten- 
sion of the leaf primordium, which keeps pace with the extension of the central 
axis with which it is fused. In the case of flowering stems the leaf-skin is formed 
by the bracts (when present) and the outermost sepals.” Miss SAUNDERS 
has gone into many details as to the extension of a aaee leaf surface in relation 
to the different eae of phyllotaxy, the various patterns deve loped, and 
other features.—J. M. C. 
Intrafascicular cambium in monocotyledons.—Mrs. ARBER,” in continuing 
her investigations of the occurrence of intrafascicular cambium in monocotyle- 
dons, has added Alismaceae, Aponogetonaceae, and Hydrocharitaceae to the 
list of monocotyledonous families, in some member of which this tissue has been 
% TELLEFSEN, Marjorie A., The relation of age to size in ene root = and 
vein islets of the leaves of Salix nigra Marsh. Amer. Jour. Bot. 9: 121-1309. 
77 SauNDERS, Eprtu R., The leaf-skin theory of the stem: a aeiieition of cer- 
tain snatomico-physiological relations in the Spermatophyte shoot. Ann. Bota 
36: dees Sigs. 34. 
ER, AGNES, pikes on eeepc cambium in monocotyledons. V. 
Ann. om 36: 251- 256. Sigs. 8. 
