ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
761 
Libani and Deodara, Pinus Strobus and sylvestris , Thuja occidentalism 
Taxus baccata, Cephalotaxus pedunculata , and Ephedra altissima. 
The author linds the apex of a growing shoot or leaf of a plant 
several years old to be occupied, not by a true apical cell, but by one or 
more, often four, cells or chambers, to which neither the outer nor the 
inner cells stand in any definite genetic relationship. There is no 
distinct outer layer or dermatogen, which has been derived direct from 
the embryo ; for periclinal divisions arise even in the outermost cells, 
and the apex is occupied by several cuj)-like layers of embryonal tissue. 
The first differentiated tissue which is formed from these embryonal 
layers is the pith, in the form of large polygonal cells, before the 
initials of either the cortex or the vascular bundles are to be detected. 
At a later period the outermost layer becomes differentiated into the 
young epiderm by the suppression of periclinal divisions, and tbe 
cortex and vascular system develope from the inner layers. In the for- 
mation of the latter the embryonal tissue which lies between the pith 
and the cortex first exhibits itself in the form of an annular zone, which 
breaks up into the procambial bundles and intermediate tissue ; a 
layer of the latter still retains its embryonal character, and becomes the 
interfascicular cambium. The further differentiation of tissues and the 
development of lateral organs are described in detail. 
Increase in Thickness of the Stem and Formation of Annual 
Rings.* — Herr L. Jost has investigated the phenomena connected with 
these processes, his observations having been made chiefly on Phaseolus 
multijlorus , Pinus Laricio, and Alnus cordata. If all leaves and buds 
are removed from a tree, there will not, in the next year, be the least 
trace of the formation of wood, indicating that the leaves have a direct 
influence on the increase in thickness of the stem. The formation of 
vessels is in fact usually in direct dependence on the formation of foliar 
organs. Between the leaf itself and the leaf-trace the author finds not 
only an anatomical, but also a physiological connection. 
Gunnera manicata.j — Dr. W. Berckholtz describes in detail the 
morphology and anatomy of this species. The flowers are hermaphro- 
dite ; the ovule is pendulous and anatropous ; the fruit is a drupe ; the 
seed contains an oily endosperm. In the course of the vascular bundles 
in its leaf-stalk, and in the bundles being closed, Gunnera manicata shows 
a resemblance to Monocotyledons ; in the relative position of the xylem 
and phloem in the bundle to Ferns. The secondary roots have no 
cambium, and the pericambium usually consists of only a single row of 
cells. The author regards the nearest affinity of the Gunneracese to be 
with the Haloragese. 
(4) Structure of Organs. 
Comparative Anatomy of Plants.^ — M. A. Chatin gives the following 
resume of the more important results contained in the most recently 
published part of his work on this subject. 
* Bot. Ztg., xlix. (1891) pp. 485 -95, 501-10, 525-31, 541-7, 557-63, 573-9, 
589-602. 605-11, 625-30 (2 pis.). 
f Bibliotb. Bot. (Luerssen u. Haenlein), Heft 24, 1891, 16 pp. and 9 pis. 
X Comptes Rendus, cxiii. (1891) pp. 337-44. 
1891. 3 h 
