ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
621 
strongly thickened and lignified ; there is no cuticle. The layer of cells 
thus peculiarly transformed appears to serve the purpose of a reservoir 
of water for the purpose of assisting in the germination of the seeds 
which commences within the capsule. 
Resin-producing Receptacles.* — Herr A. Tschirch states that purely 
lysigenous secretion-receptacles are probably rare ; in a large number 
which are ordinarily so termed the cavity is first formed schizogenously, 
its subsequent development being in a lysigenous manner. The resin or 
oil is never found in the cavity itself, but in the adjacent epithelial 
cells, and the formation of these substances must be a purely chemical 
process, since living protoplasm is never found in them, whether they be 
of schizogenous or of lysigenous origin. In Styrax Benzoin there are no 
resin-receptacles, the fragrant substance not being a product of the plant 
in a healthy condition ; it flows out copiously from wounds in the stem, 
and must be regarded as a pathological result of injury. 
Gluten-layer in the Endosperm of Grasses. f — Herr G. Haberlandt 
states that the gluten-layer (Kleberschicht) in the endosperm of rye and 
other grasses is not, as has been hitherto stated, primarily a tissue for 
storing up food-materials ; nor does it serve merely to conduct the 
diastase from the scutellum to the growing embryo; the enzyme is 
actually formed in it. As soon as germination commences, both the 
pericarp and this layer detach themselves from the rest of the endosperm. 
A similar phenomenon occurs in buckwheat, and probably also in many 
other seeds. 
Comparative Structure of the Stem of Trees, t — M. L. Flot divides 
this paper into two parts ; in the first the external morphology is treated 
of, and in the second the internal morphology of a number of types is 
carefully described and compared. 
In a plant a year old the lower part of the stem differs in structure 
from either the root or the stem proper, and the author calls this the 
tigellary region. The distribution of cork affords one of the most 
interesting morphological differences in the structure of stems. It 
may appear in five places : — (a) In the epiderm (apple). ( b ) In the 
majority of trees it forms a subepidermal layer of from 1-2 (mountain 
ash) to 20 layers ( Paulownia ). (c) In certain trees ( Bobinia ) the 
separating meristem arises in a deeper stratum, and several sub-epi- 
dermal layers are in this way atrophied. ( d ) It can appear in a 
region deeper than the cortex and near the endoderm (Rosaceas). (5) In 
Clematis , the vine, &c., it forms in the pericycle. 
A resume of the characters of the cortex is then given. The cortex 
of the cauline region of a plant a year old is similar in structure to 
that of an old branch ; an external zone with thick walls may be distin- 
guished, and an internal zone with thin walls. In the tigellary region 
all the parenchyme has thin walls. 
The general conclusions arrived at are as follows: — (1) In a plant 
a year old there are two distinct regions : the cauline and the tigellary. 
* SB. Gesell. Naturf. Freunde Berlin, 1889, pp. 173-5. Cf. this Journal, 1888, 
p. 604. f Ber. Deutsch. Bot. Gesell., viii. (1890) pp. 40-8 (2 figs.). 
X Rev. Gen. de Bot. (Bonnier), ii. (1890) pp. 17-32, 66-77, 122-36 (4 pis. and 
32 figs.). 
