ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
499 
not from the epiderm of the ovule. The whole of the endosperm, with 
the exception of this outermost layer, disappears during the maturing of 
the seed. The structure of the integument of the ovule at the period of 
impregnation differs considerably in the different genera and species 
of the order, and even sometimes in the same species. The external 
coat may consist of 2, 3, or 4 layers ; the internal coat is usually 
made up of 3 or 4, though in some cases the number is much greater, 
even up to 15. The modifications which take place in the course of 
ripening of the seed are also numerous, especially in the outer coat ; 
the outermost layer almost always becomes mucilaginous. The layers 
of the inner coat usually become more or less consolidated. The pro- 
teinaceous layer derived from the outermost layer of the endosperm is 
always persistent. 
The other orders examined were the Capparidese, Resedaceae, Balsami- 
neae, Hypericaceae, Linaceae, and Malvaceae. In all cases the ovule is 
provided with 2 integuments. In the first-named four orders the remains 
of the endosperm in the mature seed are reduced to a single layer, as in 
the Cruciferae; in the Linaceae and Malvaceae it is more completely 
retained. 
Prof. R. Chodat and Mile. A. Rodrigue* have studied the development 
of the integument of the seed in the Polygalaceae. In the section 
Orthopolygala of Polygala the ovule has two coats, each of which is 
composed of 2 layers of cells ; the testa of the ripe seed being derived 
from the primine only. A very small portion of the nucellus remains 
in the ripe seed as a band separating the integument from the endo- 
sperm. The aril is formed entirely at the expense of the primine. In 
Polygala Chamsebuxus the primine of the ovule is composed of three 
layers. 
Anatomical Characters of Persistent Leaves.! — M. G. Lalaune 
summarizes the characters, drawn from a great number of examples, in 
which persistent or evergreen differ from deciduous leaves. 
The epiderm is of normal structure during the first year, but 
towards the end of the period of vegetation the cuticle begins to 
thicken and the cell-cavities to decrease in size. In the second year 
this change continues, and there may even be a lignification of the 
cell-walls, as in Rhododendron ferrugineum. There is a tendency 
for the opening of the stomates to diminish, and for the walls of the 
guard-cells to thicken, while their cavities almost disappear. The 
hypodermal collenchyme is more strongly developed, and its walls 
become thicker and sometimes somewhat lignified. The number of 
vascular bundles varies within the same species, as is strikingly the case 
in the ivy ; the sclerome is usually strongly developed ; sclerenchyma- 
tous cells frequently occur in the fundamental parenchyme. The pali- 
sade-tissue consists of only a single layer in evergreen, of several layers 
in deciduous leaves. 
Influence of External Conditions on the Form of Leaves.t — Mr. 
P. Groom records the fact that in one and the same plant (an epiphytic 
* Arch. Sci. Phys. et Nat., xxix. (1893) pp. 319-21. 
f Actes Soc. Linn. Bordeaux, xliv. (7 pis.). See Bot. Centralbl., liv. (1893) 
p. 113. X Ann. Bot., vii. (1893) pp. 152-3. 
