62 
PROCEEDINGS OF THE PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
loss of moisture, bursts, and by its elasticity propels the 
seed, as one propels a pea from between the finger and 
thumb. Still another mode of elastic dehiscence is met 
with in one or two plants allied to the cucumber, viz., 
Elaterium, or ‘ • squirting cucumber. ” The fruit is a fleshy 
oval body with elastic walls in a constant state of tension. 
The seeds lie imbedded in a mass of pulp in its interior. 
When they are ripe the fruit drops off its stalk, leaving an 
opening at the point of attachment, and through this 
opening the seeds and pulp are shot out to a distance of 
several feet by the sudden contraction of the elastic walls. 
Of this kind of dehiscence we have no example among 
native plants, and I must apologise for digressing to 
mention it. 
Lastly, we find among grasses some in which the 
fruits are able to move over the surface of the ground, 
or even to bui’row into it to sufficient depth to cover 
themselves. These movements result from the nature 
of the awns, which remain attached to the glumes or 
bracts, which break away and remain as a covering to the 
ovary. The awns are bent or twisted, and have the peculiarity 
of being very ready to absorb or to give ofl moisture, the 
bend or spiral altering its dimensions with every variation 
in the amount of moisture. Every such change of position 
moves the ovary, but, owing to fine prominences on the 
glumes, &c., they can move only in one direction;—thus 
every movement propels it forward, and in this way the 
seeds may be pretty widely distributed after some time. 
As formerly mentioned, frequently the same methods of 
distribution are found in plants wide apart in structure, 
while in other plants nearly allied to one another the 
methods are very distinct, the adaptations being suited to 
very different agencies. And you will probably readily 
understand that such resemblances are no proof of genetic 
relationship, and such differences no proof of distance 
apart, but that they depend on environment, and on the 
conditions best suited for the welfare of the various species 
of plants. Though this paper is already a long one, I may 
perhaps be permitted to instance more fully a few ex¬ 
amples of resemblances and of differences in this view. Of 
resemblances we meet with the elongated plumose style, 
serving as a float, in Clematis and in Anemone pulsatilla 
among Ranunculacece, and again in Dryas octopetala and 
Geum montanum among Rosacea. Seeds with an uni¬ 
lateral wing occur in Coniferce (firs, &c.), in the mahogany 
tree ( Swietenia ), in Proteacece (Banksia, &c.), and various 
others; seeds surrounded with a wing in Bignoniacece, 
Caryophullacece ( Spergularia, Dianthus, &c.), Cruciferce 
(Alyssum, &c.), Liliacece, (Lilium , &c.), and others ; 
hairy seeds in 'Malvaceae ( Gossypium ), Sterculiacece 
( Bombax) ; and seeds bearing a tuft of hairs in Epilo- 
bium, in Asclepiadacece, Salicacece , and various others; 
winged fruits are present in Fraxinus, Ulmus, Betula, 
Ptelea, Angelica, Acer, Banisteria, and many other genera 
belonging to different orders. Examples of such resem¬ 
blances in widely-different plants might be multiplied 
indefinitely, but these may suffice. 
Turning now to the various modes of distribution met 
with in the same natural order, and even in the same 
genus, these are at times very different. In Otiagracea, 
we find (1) Epilobium, with capsular fruit enclosing 
very numerous small seeds, each provided with a tuft 
of hairs. (2) Fuchsia, nearly allied, but with the fruit 
a berry, and no hairs on the seeds. (3) Circaea, with 
a small indehiscent fruit (with one or two seeds), covered 
with small hooked prickles for grasping. Among Rosacece 
are numerous and very various modes of distribution. 
Looking at the arrangement of the genera in any flora 
of Scotland, we find that (1) Prunus has the fruits and 
drupes distributed chiefly by birds swallowing them, and 
voiding the seeds enclosed in the stone [e.g. , cherry and sloe.) 
(2) Spiraea has fruits that open when ripe (follicles), but re¬ 
quire to have the seeds shaken out by action of wind on 
the stems. (3) Agrimonia has one or few seedlike indehis- 
centcarpels enclosed in a tubular flower-stalk which bears 
round its edge small hooks; this part breaking off, with 
the ripe carpels enclosed, the hooks serve for grasping. 
(4) Alchemilla and Potentilla, no special adaptations. (5) 
Fragaria— strawberry—has the flower-stalk enlarged, 
fleshy, and convex, with many seed-like carpels over its 
surface. The large stalk is swallowed bearing the 
carpels, which are thus distributed when voided by 
birds. (6) Rubus— raspberry, bramble, &c.—the fruit 
is a mass of small drupes like miniature cherries, and 
is distributed in like manner by birds. (7) Geum, as 
far as concerns our native species, has the style pro¬ 
vided in the middle with a bend, which forms a hook 
for grasping when the apical half falls off, as it does when 
the seed is nearly ripe. The carpels are small. (8) Dryas 
octopetala and Geum montanum, have thestyle elongated and 
hairy, to float the seedlike indehiscent carpel. (9) Rosa 
has numerous seedlike carpels enclosed in a hollow flower- 
stalk, which becomes enlarged and fleshy, and is eaten by 
animals along with the enclosed carpels, which are thus 
distributed, (10) Cratcequs (hawthorn) and Pyrus (apple, 
pear, rowan, service berry, &c.) have the stony or leathery 
carpels enclosed in a fleshy flower-stalk so closely that it 
seems to form a part of the carpels. This is eaten by 
animals, and the seeds, alone or enclosed in the carpels, 
are distributed, when voided, to some distance from the 
