ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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europseum , Ribes alpinum , Tilia parvifolia, Pinus sylvestris , and Taxus 
baccata. He points out that the distribution of labour is not so strongly 
marked in the organs of plants as in those of animals ; thus, the epiderm 
often becomes an assimilating or aquiferous tissue. The palisade-paren- 
chyme and the spongy parenchyme of the mesophyll may both perform 
the same function, or one may replace the other. The author regards 
transpiration as always essential for the existence of a current for the 
supply of nutrient salts to the plant. 
Formation and Structure of Lenticels.* — According to M. Devaux, 
in the formation of lenticels the tissue produced on the outside of the 
generating layer always consists exclusively of true bark ; the rounded 
cells which enter into the composition of the bark represent cells of the 
phelloderm which have increased more or less in size, and have become 
separated from one another ; they are developed from a phellogen situ- 
ated at the internal limit of the layer of bark which lies above them. 
The generating layer which is found below the rounded cells is a new 
layer of phellogen intercalated within the phelloderm and regenerating it. 
The generating layer of lenticels is not usually a permanent layer. 
It ceases to be active as soon as a new layer is formed lower down in the 
phelloderm, or often also in the primary cortex. The only true bark of 
lenticels, with centripetal development, is represented by the layers known 
as the intermediate rays or closing layers ; that is to say, by suberised 
cells much more closely united and having the essential characters of 
true bark. 
Assimilating Tissue of Polygonum Sieboldii.f — Dr. L. Montemar- 
tini describes the assimilating system in the stem of this plant. The 
cortex is divided into two layers, the outer one consisting of cells with 
collenchymatous walls, the inner of rounded thin-walled cells with large 
intercellular spaces. Both layers contain abundance of chlorophyll. 
The red spots on the stem are caused by the epidermal cells adjacent to 
the stomates being filled with anthocyan which protects the chlorophyll 
in the subjacent layers from too strong insolation. 
Alterations in the Tissue produced by a Parasite.f — M. A. Da- 
guillon describes the changes produced in the leaves of Hypericum 
perforatum by the attacks of a dipterous gall-insect Oligotrophus Giardi. 
They are in the following directions. The leaf itself becomes thicker ; 
the epidermal cells increase in size and lose their wavy cell-walls ; the 
upper epiderm becomes thinner ; the mesophyll becomes less differen- 
tiated ; the veins acquire a simpler structure, the collenchyme which 
usually accompanies them disappearing; the secreting glands become 
completely enveloped in the mesophyll, losing their transparency ; a red 
pigment soluble in the cell-sap is formed in the cells near the under 
surface. 
(4) Structure of Organs. 
Teratology of Flowers.§ — Herr H. Vochting gives details of a very 
large series of observations on the anomalies in the structure of flowers, 
* PY. Seances Soc. Sci. Phys. et Nat. Bordeaux, 1897, pp. 27-8. Comptes 
Rendus, cxxvi. (1898) pp. 1432-5. f Malpighia, xii. (1898) pp. 78-81 (1 pi.). 
X Rev. Ge'n. de Bot. (Bonnier), x. (1898) pp. 5-14 (11 figs.). 
§ Jalirb. f. wiss/Bot. (Pfeffer u. Strasburger), xxxi. (1898) pp. 391-510 (6 pis. 
and 1 fig.). 
