156 BOTANICAL GAZETTE [aucust 
carrying forward a point of view suggested in 1878 by KreniTz-GERLorr. The 
sporogonium described is that of Funaria hygrometrica, although Brywm nutans 
was also studied. SaBLon states that the first periclinal division of the apical 
segments differentiates a cortical-epidermal region from a central cylinder. 
The former region continues centrifugal periclinal divisions until the last or 
so-called epidermal layer is differentiated. This late differentiation of the outer- 
most layer is a feature of the pteridophytes and not of seed-plants. The inner- 
most or oldest layer corresponds to the endodermis of vascular plants. 
central cylinder, on the other hand, shows a centripetal succession in its per 
clinal divisions, the outermost layer, giving rise to sporogenous tissue, being 
the oldest and corresponding to the pericycle of vascular plants.—J. M. C. - 
NewcompBe’® has applied three methods to the determination of the angle 
for maximum response of primary roots and stems. The method of noting the 
perception time did not give decisive results, although a shorter perception time 
for a deviation of 90° was indicated than for 1 35°. The method of noting the 
after effect did not yield satisfact y results. The method of alternate stimulation 
at go° and at 135° deviation from position of stable equilibrium gave very positive 
results in favor of the former angle. These results discredit the conclusion of 
Czapex that the strongest stimulation occurs at a deviation of 1 35°. 72a author: s 
conclusion, recently announced, that orthotropic roots and stems do not receive 
equal stimulation at equal angles above and below the horizontal, is withdrawn, 
and support is given to Firtrve’s view that equal stimuli are received at equal 
angles above and below the horizontal.—Raymonp H. Ponp. 
Ficpor?? finds that the sheathing leaf base of grasses, in addition to protecting 
and supporting the unfolding bud, performs the function of a guiding ongat 
While the growing apex of the young shoot is still enclosed by the cotyledon, the 
latter, being sensitive to light and gravitation, assumes a favorable position into 
which the emerging leaf is directed. Coincident with the protrusion of the leaf 
the growth of the cotyledon ceases and its sensitiveness to light and gravitation 
disappears. This guiding function of the cotyledon is then assumed by the 
sheathing leaf base, as the author finds, by virtue of its sensitiveness to light 
and gravitation. The blade is not sensitive to light, but the vaginal sie 
the sheath are and in such portions the sensibility is uniform. The evidence sgh 
regarding the sheath as sensitive to gravitation might be more convincing~ 
Raymonp H. Ponp. 
GHLY SPECIALIZED plant cells and_ their peculiarities are discussed bY 
Davis"* in a continuation of his studies upon the plant cell. The forms om 
—————— 3 
: fee 
"© NEwcomsg, F. C,, Geotropic response at various angles of inclination. se 
Botany 19:311-323. 190s, a 
B *7 Ficpor, W., Ueber Heliotropismus und Geotropismus der Gramineenblatter a 
er. Deutsch. Gesells. 23:182-1091. 1905. 
8 . : i ia 
a5 Pian B. M., Studies on the plant cell. III. Section 3. Highly spe#™ 
piant cells and their peculiarities. Amer. Naturalist 38: 571-594, 725-760. aint 
