ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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from the application of the dragging force of strings stretched over 
rollers and weighted. The hypocotyl of a seedling sunflower which 
was ruptured by a weight of 160 grm., bore a weight of 250 grm. after 
being subjected for two days to the strain of a weight of 150 grm. ; after 
a few days the weight was increased to 300 or 400 grm. without injury. 
Seedlings of Phaseolus which were ruptured by a weight of 180 grm. 
could, after seven days, resist a strain of 650 grm. after being subjected 
to one of 165 grm. Leaf-stalks of Helleborus niger (Christmas rose), with 
a limit of resistance amounting to about 400 grm., were able to resist 
one of 3 '5 kil. after about five days. Similar increase in firmness was 
demonstrated in other stems and in tendrils, as well as in the case of 
etiolated plants. The increase in strength is effected by a strengthening 
of the cell-walls, generally accompanied by a great increase in the col- 
lenchyme. Bast-fibres already in existence are greatly strengthened, 
and they may be called into existence where they do not previously 
occur, as in the leaf-stalk of Helleborus niger. The strengthening of 
the mechanical elements is accompanied by a retardation of the growth 
in length. 
(4) Structure of Organs. 
Hairs on the Corolla of Pinguicula.* — Prof. A. Weiss describes 
the capitate hairs in the throat of the corolla of Pinguicula vulgaris , 
which he states to have no secreting function, but to be probably con- 
nected with the fertilization of the flower through the agency of insects. 
When mature all of the numerous cells of which the hair is composed, 
with the exception of the basal one, are strongly cuticularized, the cuti- 
cularization taking the form of interrupted spiral bands. Intermediate 
between the cells which form the pedicel and those which form the head, 
is usually an intermediate cell containing, like the head, a yellow fluid, 
while the cells of the pedicel contain a violet fluid ; both, however, dis- 
appearing in old hairs. The head may consist of a single globular cell, 
or may be divided into a number of cells. Each hair originates from a 
single epidermal cell; the pedicel-cells are always formed first, the head 
being a later production. All the cells of the hair contain abundance 
of protoplasm, which is in active rotation. 
Dorsal Position of Ovules in Angiosperms.f — M. G. Chauveaud 
states that in the Asclepiadeae ( Vincetoxicum officinale') the ovules are 
produced on two placental wings which, from a morphological point of 
view, occupy the inferior or dorsal face of the carpellary leaves. He 
considers that this tends to break down the essential difference which 
has hitherto been supposed to subsist between Gymnosperms and Angio- 
sperms, in the ovules being borne in the former on the inferior, in the 
latter on the superior face or margins of the carpels ; also that there is 
a more complete homology than had previously been supposed between 
the male and female organs in Angiosperms. 
Classification of Fruits. £ — M. G. Beauvisage proposes a classification 
of the various kind of fruit into the four divisions of berry, drupe 
* SB. K. Akad. Wiss. Wien, c. (1891) pp. 276-83 (1 pi.). 
f Comptes Kendus, cxiv. (1892) pp. 141-3. 
X ‘Remarques s. 1. classification des fruits,’ 74 pp. and 1 pi., Lyon. See 
Bonnier’s Rev. Geu. de Bot., iv. (1892) p. 188. 
