INTELLIGENCE OF PLANTS.

Timaru Herald, Volume XIIC, Issue 13881, 19 April 1909, Page 3

INTELLIGENCE OF PLANTS.

Have plants intelligence F Do they think? Can they.see, hear, and feel"? Is it an nnjust reflection upon the vegetable kingdom to call a man a cabbage head? is there an ethical and humanitarian basis for the park legends warning the public to keep oft' the grass? How soon will vegetarians who denounce the cannibalism of meat eaters be convicted of cruelty in devourtheir sentient fellow-beings, such as potatoes, turnips, and onions? Will the human race become too tenderhearted to cut the throats of pallid lilies and to strangle sobbing little pansies in their beds ? PLANT NERVES AND EVES. " These questions are not suggested by the belated ravings of an Elizabethan poet of the mystic fancies of a Brahmin thinker getting up an exclusive lecture course at the St. Regis. Scientists of repute and sobriety are responsible for the issue of plant intelligence. Professor Francis Darwin, son of the illustrious discoverer of evolution, started the ball rolling at the last meeting of the British Association in Dublin, when 1 he declared that plants respond to touch, like animals, have memory, develop habits, and exercise as much free will as any anti-Calvinist. Next Professor Harold Wager, the well-known botanist, came along, asserting that the outer skins of many leaves act as eyes, which focus the rays of light on the interior of the leaf, and carry an impression to the plant brain. The lenses of the vegetable eyes, he says, are so accurate, that photographs can be taken by means of them. Photographs of men and landscapes, lehsed by plant eyes, were exhibited bv Professor Wager. There was no doubt of plant intelligence from the days of Homer until the scientists of the nineteenth century did away with the last vestiges of anthropomorphism. Science, in wrathful reaction against the miraculous, banished all poetical conceptions, sent wood nymphs and dryads to Coventry, and established the universe on rigid mechanical and business lines. • The laughing grain, the weeping willow, and the modest violet were consigned to the limbo of fancy.

A reaction gradually came about, however, owing to the exhaustive botanical researches of such men as Noll, Haberlandt, and Nemec. The simple mechanical explanations were not found sufficient to account for the complex phenomena of plant liie. Startling similarities between animal and vegetable organisms were discovered. Professor Haberlandt published in 1904 his discovery of plant eyes, thus antedating the recent announcement of Professor Wager., In support of the intelligence theory, it may lie cited that plants constantly move about except . when they sleep, avoid obstacles at a distance, send their roots unerringly after water, reach for support with their tendrils, shut their leaves when touched, slant their leaves to avoid excessive sunlight, and sometimes smell and reach after animal food like beasts of prey. There are five, hundred species of carnivorous plants. A tree, it is recorded, accidentally planted in an oak crotch, sent down its root to the ground and the root divided eighteen inches above a stone so as to get over it on either side. Apparently the root solved the problem of dodging the stone a foot and a half before reaching it. The coloured hybrid nicotiauas open their petals in the day, as if aware that their hues would be wasted on the insectless dark hours when the white variety is open. The adult blue gumtree of Australia turns its leaves edgewise to the zenith to avoid the scorching heat of the sun, while the young shaded tree saves itself this exertion. Many plants have a rhythmic swaying movement in their sleep. Electric light stops their movements, and produces ah injurious insomnia. A plant compelled to keep , awake looks pale and fagged out. The different sleeping hours of plants liave enabled botanists to construct flower clocks. Plants respond to the'light,-and continue to bend toward it halt an hour after the light is withdrawn. THE "REASONING" OP THE PLANT. Many instances of vegetable reasoning or something else are given by R. H. France in his "Germs of Mind .in .Plants." The rootlets of .plants, which Charles. Darwin compared to a brain, have a sense of the nearness of water, called hydrotopism, and they have a sense of gravity, termed geotropism. The tendrils of a hop-vine swing in wide circles around a chosen branch. Once they have touched it they seize it in about twenty seconds, and acquire such a hold in an hour that it takes force to tear them away. Then the tendrils curl up like a corkscrew, and this shortening pulls up the vine. The sensitive plant is proverbial. If a branch is touched, the feathery leaves rise, fold together, and the stem sinks down. A real injury to the branch sends a shudder through the entire plant, which closes every leaf in sympathetic woe. This momosa is liveliest in its native Southern haunts, and seems a little stupefied in Northern hothouses.

The flowers of the barberry cunningly compel the bees to perform a useful service. Baited with tiny cups of honey, the six stamens lie down against the yellow petals, and wait for a bee to release tile trap, when they spring up and shower hnn with pollen. The bee' acts as involuntary messenger, taking the jiollen to another flower, if the employment of insects for fertilisation does not seem conclusive evidence of intelligence, there is the case of a Central American acacia which houses a standing army of black ants in holes bored in the thorns, ajid feeds them with sausage-like growths at the ends of its leaves, which vegetable sausages might be compared to the travelling ration of the Germany army. The function of the ant army is to defend the trees against bands of leafcutting ants, which destroy all other vegetation, and it is said the acacia's soldiers fight in its behalf with valiant success. There is also a species of fern which goes into a mysterious partnership with ants, whom it provides with little dwellings down the sides of its roots.

There are many predatory and tigerish plants, of which the sundew is a notable example. It catches insects in a hairy trap, and digests them with pepsin,, the same as human beings and other animals do. The leaf jaws will grasp a pebble, but make no attempt to digest it, and soon the jaws open and let the pebble fall to the ground. Portuguese farmers use the fly-catching ilrospliyllum instead of mechanical flytraps to clear their houses of insects. In the tropics the stench of decaying insects proclaims the presence of plants with pitcher traps full of P r °y- A plant without roots that sails 111 ditches and ponds seeking insects whom it may devour is the Aldrovandi vesiculosa. Unsuspecting water fleas and skippers touch the bristles of its thick valved leaves once, and no more; tney are seized and consumed. SOME VEGETABLE ORGANS. It is the co-operation between the plant parts and the subordination of individual inclinations to the general welfare that argue most strongly for plant intelligence. A number of vegetable sense organs have been discovered iy Professor Haberlandt. lie has found that plants are endowed with nerves the same as animals, and these nerves are generally excited hy irritable hairs,

which are like the whiskers of a cat. The sensitive tendril spurs itself to activity by rubbing its cells ; against a deposit of crystallised acid; the irritation is produced when it meets an obstacle. The mechanism of various ' flytraps is based on a hydraulic principle, water pressure being transmitted from cell to cell to operate the valves. A gravity organ is possessed by all the lower "water animals, to enable them to" tell when they are standing on their feet or are upside down. The snail carries internally a ball of liirw, which rolls in a spherical water pouch, and, by rubbing against bristles informs the owner of his position. Similar gravity organs have been discovered in plants by Professor Haberlandt. There are starch grains stored in large cells, which enable the plant to growupright. Without these starch kernels the plant acts as if dizzy, and becomes bent.