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POPULAR SCIENCE REVIEW. 
England, if the plant found by Mr. Briggs near Plymouth, and called by 
Dr. Boswell-Syme 1 Pyrus communis, var. Briggsii,’ be the same — and no- 
where else in Europe. Both countries had their western shores occupied, 
anterior to the invasion of the Cymry, by a peculiar race of people having 
strong Oriental characteristics, and which people some authors describe as 
occupying the country as far north as Argyllshire — the evidences of such 
occupation having been laid before the British Association at Bristol in 
September 1875, in Dr. Phene’s paper on that subject — while the same tree 
is found on Mount Elbruz in North-east Persia — a country not remote from 
that which formed the arena of Arj una’s exploits, and whence it would seem 
to have been imported to the west of Europe.” 
On Floral Aestivation. — The Rev. G. Henslow read a paper on the above 
subject before the Linnean Society on June 1. Mr. Henslow referred to 
his previous paper read before the Society, in which he regarded the opposite 
as the fundamental arrangement of phyllotaxy in Dicotyledons, and described 
the various modifications of imbricate aestivation. Starting from the ordi- 
nary pentastichous or quincuncial mode, in which two leaves of the cycle 
are external and two internal, whilst one is half outside and half in, special 
attention was called to the “ half-imbricate ” and “imbricate proper” 
methods, in both of which there are one external, one internal, and three 
intermediate leaves ; the “ imbricate proper ” is converted into the convolve 
mode, in which all the leaves are intermediate, by the first leaf of the cycle 
being overlapped by the adjacent third leaf. The “vexillary” and “cochlear” 
modes, and those of many other irregular flowers such as Cassia , are to be 
referred to the “ half-imbricate.” The author agreed with Professor A. Gray 
in distinguishing “convolute” from “contorted.” A new theory of the 
nature of cruciferous flowers, which derived them from a primary type by 
symmetrical reduction of the parts in each whorl, was explained; and 
chorisis was objected to as an explanation of the pairs of long stamens. The 
frequency with which the corolla is found to develope subsequently to the 
stamens was also mentioned in objection to Pfeifer’s view of the corolla of 
Primula being an outgrowth of the andrcecium. 
The Hygroscopic Mechanism by which Seeds bury themselves was some 
time ago the subject of a paper read before the Linnean Society by Mr. 
Francis Darwin, the son of the celebrated naturalist, and it is thus reported 
by the “Journal of Botany” (No. 161): — “The seeds observed were those 
of several grasses and of Anemone montana , but Stipa pennata was specially 
examined. This has a strong awn, the lower part vertical and twisted with 
two knees, and a long horizontal upper feathered portion. Moisture causes 
the spiral portion to untwist and the horizontal part to revolve, the knees 
disappearing and the whole awn becoming straight ; drought reverses the 
process. In nature the flat feathered portion is readily entangled in vege- 
tation, and the seed rests vertically with its point on the soil. When the 
spiral untwists with moisture, the horizontal part being prevented from 
revolving, that motion is transferred to the seed, and to this being added 
pressure on its point it becomes screwed into the ground. With dryness 
and the reversal of the screw the seed is not drawn out again, but curiously 
is thrust deeper down by additional mechanism. Heat acts in the same way 
as moisture. The cause of torsion as explained by Hildebrandt and Hanstein 
