622 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
squirrels and other animals, while in the case of Pterocarya the dissemi- 
nation is aided by the wings of the fruit. 
Leaves of Viburnum.* * * § — Sir John Lubbock points out and attempts 
to explain the remarkable difference between the leaves of our two native 
species of Viburnum , — V. Opulus and V. Lantana. The former have 
stipuheform appendages, while the latter are entirely exstipulate ; the 
former have honey-glands at the base of the lamina, the latter have not. 
The former of these two differences he attributes to the different way in 
which the leaves are folded in the bud, in consequence of those of V. 
Opulus being three-lobed, those of V. Lantana not lobed. The honey- 
glands probably serve to protect the young and tender leaves of V. Opulus , 
which are quite smooth, from the attacks of caterpillars and other 
insects, while the leaves of V. Lantana are otherwise protected by a felt 
of hairs. 
Form and Function of Stipules, j — Sir John Lubbock adduces a 
number of examples where, within the same natural order, some species 
have stipulate, others exstipulate leaves, and endeavours to arrive at a 
general law governing the presence or absence of stipules. He believes 
that, as a general rule, the difference has reference to the mode of pro- 
tection of the bud. This protection may be effected in various ways, — 
by the stipules, by the base of the leaves, by the more or less expanded 
base of the petiole, by the pedestal of the petiole, by scales, by hairs, 
by gummy secretions, &c. Sometimes, also, the stipules assume the 
function of the leaves themselves, or they become spiny and serve as a 
general protection to the plant, or they are glandular, Ac. 
Pearl-like Glands of the Vine.! — According to Herr H. Miiller- 
Thurgau, the small pearl-like structures which occur on the young 
branches and leaves of most, though not of all, varieties of the grape- 
vine, are of a trichomic nature. They are usually spherical, and are 
elevated on a short pedicel ; from ten to twenty large cells are covered 
by a small-celled epiderm, usually provided with one stomate to each 
gland. Their formation is independent of the vigour of the plant or of 
the moisture of the air. Their purpose appears to be to serve as pro- 
tecting organs against the attacks of small animals. 
Roots springing from Lenticels.§ — Herr H. Klebahn describes the 
roots which spring from beneath the lenticels in the stem of Solanum 
Dulcamara, often even at a considerable distance from the soil. These 
roots possess a well-marked root-cap, dermatogen, periblem, and 
plerome. 
Somewhat similar structures are found in Herminiera Elaphroxylon, a 
floating plant belonging to the Papilionaceee from the Nile region ; and 
here also are remarkable tubercles on the roots, the tissue of which is 
partly of an aerenchymatous character. They contain also, beneath the 
cortical layer, a bacteroid tissue of the same nature as that in the tubercles 
of many other Papilionaceae. 
* Journ. Linn. Soc. (Bot.), xxviii. (1891) pp. 244-7 (1 fig.). 
t Tom. cit., pp. 217-43 (11 figs.). 
X Weinbau u. Weinhandel, viii. (1890) pp. 178-9 (1 fig.). See Bot. Centralbl., 
xlvi. (1891) p. 362. 
§ Flora, lxxiv. (1891) pp. 125-39 (1 pi.). 
