When an insect is caught or a piece of raw meat is placed on the leaf, the blades close up and the glands immediately pour out a fluid which is practically similar to the gastric juice of the animal stomach in its digestive properties. The matter of the insect body or of the meat is thus absorbed into the substance and tissues of the plant just as the food eaten by an animal is digested and goes to build up its fabric or repair waste.

The animal digestion can only be carried on by the brain-force acting by means of a nerve upon the gastric glands. We may therefore concede that it is the action of the same power in the plant that produces the same effect. The motor is absent but the motion is there. This movement in plants when irritated and the act of digestion is seen also in the Sundew, and there are many species in whose flowers and leaves muscular movement is seen when irritated.

The Hedysarum of Bengal is an example of movement without external cause. This plant gyrates the central leaflet of its pinnule. The properties of its lateral leaflets are, however, the most remarkable, for they have a strange power of jerking up and down. This motion will sometimes stop of its own accord, and then suddenly, without any apparent cause, commence afresh. The leaves cannot be set in action by a touch, though exposure to cold will stop the motion. What is more amazing in the movements of these leaflets is, that if they be temporarily stopped by being held, they will immediately resume action after the restraint is removed, and, as if to make up for lost time, will jerk up and down with increased rapidity.

The power of spontaneous movement is also seen in the seed spores of certain seaweeds and other lowly plants. These spores move about in water with freedom, and the filaments of many of the liverworts exhibit a capacity for extraordinary motion. In the spores of the potato fungus (Pythoptora infestans) we have another wellmarked instance of the power of movement according to circumstances. When the spore-cases burst, a multitude of little bodies escape and if these gain access to water-a drop of dew on the potato leaf for instance—they develop a couple of curious little tails, by means of which they swim about after the manner of tadpoles.

Then there are the unicellular plants, the desmids and diatoms, which dart about hither and thither in the water. It is noteworthy that all these movements can be arrested by the application of chloroform or a weak solution of opium or other soporific.

It is not in the fully developed vegetable organism alone that we

find evidence of the existence of brain-power, but this power begins to display itself with the sprouting of the seed. In the commencement of plant life we find, as in the case of the pea (to give an easily tested example) that the root emerges at one end of the seed and the shoot at the other. What causes the former to descend and the latter to ascend? If the seed is so placed that the root comes out at the top, the result is the same, for the root immediately turns round and grows downward and the shoot vice versa. This cannot be caused by gravitation, although Darwin once thought so, as the force of gravity would have the same effect on the shoot as on the root. There can only be one reason, and that is the existence of a directing force or brain-power.

There is no structure in plants more wonderful than the tip of the root. The course pursued by the root in penetrating the ground is determined by the tip. Darwin wrote: "It is hardly an exaggeration to say that the tip of the radicle, endowed as it is with such diverse kinds of sensitiveness, acts like the brain of animals."

It is unnecessary to adduce further illustrations in proof of the fact that brain-power can, and does, exist apart from a visible brain. When we see the irritability of the sensitive plant, transmitted from one part to another, exhausted by repeated artificial excitant, and renewed after a period of repose, it is difficult to dissociate it from animality. Still less can we witness certain organs taking determinate positions and directions, surmounting intervening obstacles, moving spontaneously, or study the manner in which they are affected by stimulants, narcotics, and poisons, and yet declare these phenomena to be caused by a different power which produces similar actions and effects in animals. Vital activity is the rule and inertness the exception in plant life; and this fact seems to impress upon us the error of that form of argument which would assume the non-existence of the higher traits of life in plants merely because the machinery is invisible.

It has already been mentioned that the lowest forms of both animals and plants are individuals whose bodies are merely single cells. It is worthy of note too that the earliest embryonic state of all the higher animals is merely that of a single minute cell. It is a wonderful fact that the embryonic forms of plants and animals, birds and beasts, fish and fowl, the Mimosa and man are so exactly similar that the highest powers of the microscope are unable to trace any distinction between them. From an evolutionary point of view there is nothing after all so very wonderful in this. If there were no signs of intelligence in the vegetable kingdom the cause for wonder

would be greater. If thought is the product of evolution, it must have had its beginnings. The reason why the intelligence of all living organisms has not reached to the same stage as that of the genus homo, is merely because in them the evolutionary process appears to have stopped. For anything we know it may have taken as many thousand years to evolve the intelligence of the Mimosa as it has that of man, although of course the latter is an incalculably greater distance ahead. As Professor Drummond says: "Mimosa can be defined in terms of man, but man cannot be defined in terms of Mimosa." This problem of the evolution of intelligence is one to which we are naturally led when considering the intellectual traits of lower organisms, but to consider it even in a superficial manner would be beyond the scope of this paper.

ARTHUR SMITH.

RAILWAY PASSENGERS AND

THE

TUNNELS.

HE Londoner is easily diverted, and one of his chief sources of amusement some years ago was the erratic route of the Underground Railway. John Leech, it may be remembered, gave an entertaining sketch in Punch indicating the surprise of the domestics in a town house at the sudden appearance of a stoker's head through the kitchen floor, with the polite remark: "Excuse me, marm; but can you 'blige me with a scuttle o' coals, as the water in the hengine 'as gone horff the bile?" Since the appearance of this skit the railway traveller to and from and round about the city has endured much on the subterranean line. A special providence seems to have safeguarded him from asphyxia; still he is prone to gasp and curse as he inhales the remarkable atmospheric compound that broods over the steel track of the Metropolitan. With the object of making his journey more pleasant, a special committee sat last year to consider the best methods of tunnel ventilation; and it is possible that with the help of science, assisted by the purse of Fortuna, the underground way will yet be fit to live in.

Tunnels have since the inception of the railway system been a source of perplexity to engineers, and of fear and annoyance to passengers. Half a century back the tunnel was a gruesome burrow, arousing so much consternation and dread that it threatened for a time to kill railway enterprise. It was gravely asserted that if the passenger got through it alive, the chill or the noxious air would give him a shock severe enough to undermine the strongest constitution. So objectionable did the thought of tunnel-travel become that a party of experts was organised to go through the tunnel beneath Primrose Hill, in order to reassure the railway traveller that there was no danger either to physique or lungs. These experts reportedthey were sanguine men-that they found the tunnel dry, of an agreeable temperature, and free from smell. They did not notice

effluvia of any kind. The lamps in the carriage were lighted, and in their transit the sensation experienced was precisely that of travelling in a coach by night between the walls of a narrow street. In fact, they were rather delighted than otherwise with their exploit, and expressed the opinion that tunnel-travelling was by no means detrimental to health.

Lieut. Le Count, an authority on early railway construction, did all he could to strengthen the faith of the passenger in this matter, writing: "So much has been said about the inconvenience and danger of tunnels that it is necessary, where there are yet so many railways to be called into existence, to state that there is positively no inconvenience in them, except the change from daylight to lamplight." All men are not philosophers, however, and one passenger took a more serious view of the vicissitudes of underground travel. This gentleman, in the days when it was customary to hoist private equipages on low trucks attached to the train, resolved to journey to Brighton in his own carriage. "In Balcombe Tunnel the truck conveying his carriage became disengaged from the train. The unfortunate occupant, perceiving the train leaving him, called after it, but in vain; and finding it proceeded on its journey he became dreadfully alarmed, being afraid to alight, and not knowing whether in a few minutes he might not be dashed to pieces by the next train. He had not been long in this suspense when an engine entered the tunnel, puffing away and the whistle screaming. He now considered his doom sealed, but the engine proved to be a pilot one sent to look after him, the truck and carriage having fortunately been missed on the train arriving at the next station."

Some passengers were fearful lest they should be drowned by sudden inrush of water from hill streams; others were apprehensive that the sudden concussion of air caused by the passage of the locomotive would so violently shake the brick fabric of the tunnel that the arch would collapse, and they would be crushed to death. The latter disquietude particularly related to Box Tunnel, and it was not allayed till General Pasley, under instructions from the Board of Trade, thoroughly inspected the tunnel and reported that it was perfectly sound. By-and-by the confidence of the passenger in the security of underground travel became greater, and he confined his criticism rather to the repellent condition of the atmosphere than to the probability of tunnel fall. He read, it is true, with a certain amount of unrest, of the perils of tunnel-making-how in some instances the water broke through the quicksand or gravel, and the men had to be rescued on rafts; but he hoped for the best,