Part 14

I would teach Latin and Greek only to older boys, and by the method in which we all learn a modern language--that is when we have the advantage of being at once teacher and learner. I mean by reading quickly, with a translation if necessary; at first without understanding half of what we read, but gradually picking up words as we go along. This is how I learned to read easy Italian. By the advice of the late Henry Sidgwick I began on a bad Italian translation of a French novel, because such a version, being full of French idioms more or less literally translated, is easier than idiomatic Italian. The right book to begin on is a good murder story, such as one of Gaboriau's, which are fortunately to be had in bad Italian. What would an old fashioned teacher of Greek and Latin have said to this! In my own case I feel that the _difficulty_ of reading the classics was good discipline, and so far educational. In Henry Sidgwick's method one is carried along by the detective business, and learns Italian words as a child picks up its own language, by context and re-iteration. It will be said that this method is not applicable to Latin and Greek, and that even if it were so, it would not be educative. I confess I do not expect my words to sink into the hearts of the teachers of what are unkindly called the dead languages. The great Moloch of examination has constantly to be supplied with human children, to say nothing of grown-up people. Some escape, but how many are reduced to ashes?

I have said nothing about what should have been my theme, namely, the beginning of the College year. To my thinking beginnings have something of the melancholy that seems more appropriate to endings. Sad associations tend to adhere to all that has the quality of periodicity. I for one feel this when spring once more puts on the familiar look with which our childhood and youth seemed to mingle on equal terms, but which upbraids us now we are no longer young.

And in a more work-a-day spirit Monday morning is sad. I think this is so because the conception Next Week is full of the ghosts of dead resolutions. No doubt it was on Monday mornings that Mr. Shandy renewed his vow to have the hinge of the parlour door mended, which I think remained unrepaired to the end of the book.

But after all, this gloomy point of view belongs to the onlooker, not to the actors in the rhythm of things. Each particular Monday is a new-born entity, and doubtless feels a pleasurable excitement in its brief life. And to the actual snowdrops and winter aconites that pierce the cold ground, spring is a new and glorious experience. In this academic springtime (which chances to occur in autumn) the onlooker need have no morbid feelings, only perhaps a touch of envy of those whose College life begins to-day.

XIII PICTURESQUE EXPERIMENTS

To those who have never made experiments on plants it may seem that 'picturesque' is an odd term to apply to laboratory methods. But to an experimentalist the adjective does not seem overstrained. There is not merely the pleasure of seeing a prediction verified--that may be experienced in more everyday matters. There is a peculiar delight in the discovery of a method of revealing some detail in the natural history of living things. I remember vividly the pleasure which I felt when I first tried the experiment on _Sorghum_, described in the essay on the Movements of Plants in this volume. {210} I hoped that the seedlings would curve in the elaborate manner shown in Fig. 4. But I had so little expectation of success that I did not explain the object of the trial to my laboratory assistant, and it came as a shock of delight when he told me that the seedlings had "curled up like corkscrews." I do not think that it is an exaggeration to say, that this result is a picturesque illustration of the distribution of gravitational sensitiveness in plants. The instances in the present essay are not concerned with the movements of plants, and are so far less interesting, but I think the reader will not refuse them the same adjective.

We all know that in plants--from the smallest weed to the giant trees of America--there flows a stream of water from the root to the topmost leaf. Nevertheless, it is an experience to have ocular proof of this life-giving current. A branch of laurel is so arranged that it has to suck up the water it needs through a coarse thermometer tube, dipping into a beaker. The laurel does not wither, and we know therefore that it is continuously supplied with water. If the beaker is removed we shall see the absorption, for the thermometer tube does not remain full of water; a minute column of air is seen at its lower end which rapidly increases in size, and finally when the tube is emptied of its water-content, bubbles of air escape one after another into the larger tube, which contains the cut end of the branch. This, the simplest possible experiment, is nevertheless a vivid ocular proof of the laurel's power of absorbing water. It can be shown that the sucking power of the branch depends on its leaves, for if these are removed the rate of the current is very greatly diminished. It can also be proved that it depends on some quality of the leaf surface, for if a new specimen is taken, and if the lower sides of its leaves are rubbed with vaseline, the rate of absorption will be seen to diminish very greatly. Greasing the upper surface of the leaves does not produce this result, and when we examine the two surfaces it is found that the lower one is riddled with innumerable microscopic holes (stomata), while the upper side of the leaf has no such apertures. The stomata in fact are the arbiters of what shall pass in or out of the body of the leaf; they are the gate-keepers who regulate both export and import. They are known by actual inspection (with a microscope) to close at night: the result of this is that the evaporation of the leaves is much slower at night, and this is true when allowance has been made for the fact that evaporation is also checked at night by the dampness of the air.

[Picture: Fig. 7. The Porometer]

The microscopical inspection of stomata is not a completely satisfactory method of discovering to what degree they are open. It has, however, been my good fortune to resuscitate and simplify a method of studying the stomatal condition. The method was many years ago tried in a hopelessly cumbersome form by a German, but never came into use. My apparatus is described in the _Proceedings of the Royal Society_, {212} and is known as the Porometer. Its essential part is shown in Fig. 7. It consists of a funnel-shaped tube, having a broad flange, which is cemented on to the stomata-bearing surface of a leaf. The leaf is represented by the obliquely shaded object and is enormously magnified. To the upper orifice of the funnel is fixed a rubber tube, and by means of it steady suction can be supplied. The result is that a current of air is drawn through the stomata into the leaf, and then out of the leaf into the cavity of the porometer. The rate of this current is an index of the degree to which the stomata are open. With this apparatus a number of interesting points can be determined.

[Picture: Fig. 8. Curve of Porometer readings in light and darkness (black)]

Fig. 8 shows the effect of alternate periods of light and darkness. The fall of the curve represents partial closure, and is seen to occur in the periods of darkness (black), and to rise when the plant is re-illumined. These changes are necessarily accompanied by rise and fall in the evaporation of the leaf, but into the question of the accuracy of this correlation I shall not enter.

There are other methods of demonstrating the movements of the stomata. Stahl had the happy inspiration of making use of the colour-changes of cobalt chloride. A piece of filter paper soaked in a 5 p.c. solution of this salt is blue when dried, and turns pink in damp air. A dry piece of this material, applied with proper precaution to the stomata-bearing surface of a leaf, rapidly changes to pink if the stomata are open. When, however, the same trial is made on the upper surface of a leaf, where stomata do not occur, no such change occurs. If two leaves are treated at the same time, one in the normal position and the other upside down, it is delightful to watch the appearance of a pink picture of that leaf whose stomatic surface is in contact with the paper, while no such change takes place over that which exposes no stomata to the tell-tale material. Another method was discovered by the accident of finding in an old house in Wales a Chinese figure of a man, cut out of a thin shaving of horn, which writhed and twisted when placed on the hand. It was clearly very sensitive to moisture, and it seemed possible that horn-shavings might be used to test the condition of the stomata. The first difficulty was to obtain a supply of this material. Having discovered from the P.O. Directory that there were two horn-pressers in London I proceeded to visit one of them somewhere in Hoxton. He turned out to be of a highly suspicious disposition, but his wife had more discernment, and persuaded him that I was a harmless customer, with no designs on trade secrets, and I finally obtained what I wanted. A delicate strip of horn was fixed to a little block of cork and placed on a leaf, and to my delight showed the stomata to be open by violently curving upwards. It was only necessary to fix a graduated arc to the cork, and to fasten a delicate hair on to the horn so as to serve as index. The instrument is not of course accurately quantitative, but it does at least show whether the stomata are nearly shut, moderately open, or widely so. Rough as it is I found it good enough for determining a number of interesting facts in the physiology of stomata. {215a}

I now pass on to a different subject, the all-important process on which the life of green plants depends, an act therefore by which our own existence and that of all other animals is conditioned. I mean the process known as _assimilation_. This is the truly miraculous feat of using as a source of food the carbonic acid gas (CO2) which exists in minute quantities in the atmosphere. The plant is in fact a carbon-catching machine, and the machine is driven by the energy of the sun, and can therefore only work in light. The eminent Russian botanist, Timiriazeff, in a lecture on this subject {215b} before the Royal Society, made a witty use of _Gulliver's Travels_--a book not commonly quoted as an authority in scientific matters. He pointed out that the philosophers of Lagado, who were extracting sun-beams from cucumbers, were not doing anything absurd. On the contrary, since the cucumbers had been built with the help of sunshine, it was a reasonable expectation that energy corresponding to the sunshine should be obtainable. This indeed is what we do when we drive a steam engine by burning coal which ages ago was built by vegetable machinery driven by sunlight.

It is possible to show the existence of this process by very simple experiments. The most direct, but the least interesting, experiment is to take two similar plants, and expose plant _A_ to an atmosphere containing CO2 while _B_ is in air freed from that gas. Both specimens are placed in bright light, and after a sufficient interval of time their leaves are tested for the presence of starch. This is a simple matter; the green colouring matter is washed out of them by means of alcohol, and they are then placed in a dilute solution of iodine, which has the property of staining starch purple. It is always pleasant to see the leaf that had been supplied with CO2 turn blue, while the starved leaf remains a hungry yellow.

Some of the prettiest methods of demonstrating this process depend, not on the manufacture of starch in the leaf, but on the fact that an assimilating plant sets free oxygen, by breaking up the molecule CO2, building the carbon (C) into its own tissues, and letting the oxygen (O) go free. A beautiful method was discovered on these lines by Engelmann, which I was never tired of seeing year after year in my Cambridge class. Defibrinated bullock's blood is freed from air by means of an air pump and charged with CO2. In the course of this process it acquires the dingy tint of venous blood. A single leaf of the American weed (Elodea) is mounted on a glass slide in a drop of this blood and covered by an ordinary cover slip. Then comes the dramatic moment: the preparation is exposed to sunshine, and in 3 or 4 minutes a delicate scarlet border begins to appear round the leaf and grows rapidly, making a curious sunset effect in contrast with dingy purple of the venous blood. The meaning is very clear; the Elodea leaf in sunshine took the carbon from the CO2, and the oxygen thus set free gave the venous blood the scarlet hue characteristic of the arterial condition. Professor Farmer has designed a striking method based on another well-known experiment of Engelmann's. A drop of water containing the products of decay, and therefore swarming with bacteria, supplies the test. A drop of this fluid is placed on a glass slip, one or two delicate leaves of a green water plant (Elodea) are added, and a square of thin glass is placed on it. Round the edges of the cover-slip the preparation must be sealed with a preparation of wax, which melts at a low temperature, and when cold serves to prevent the preparation drying; it also isolates it from the surrounding atmosphere. After making sure under the microscope that the bacteria are in active movement, the glass slip is placed in the dark for some 3 or 4 hours. It is then examined, and the bacteria will be found to have ceased to move because they and the leaves between them have consumed the oxygen dissolved in the water, and bacterial activity being dependent on oxygen naturally came to an end. The preparation is placed under the microscope and illumined with bright incandescent gas, and after a short time the bacteria begin to stir and are soon once more whirling in their insensate dance. The reason is obvious--the green leaves under the influence of light were able to seize the carbon from the CO2, and the O thus set free put the bacteria in motion. The bacterial dance is therefore evidence of the act of assimilation carried on by the Elodea leaf.

Yet another method is worth mention, viz., that of Boussingault. The plant is placed in an inverted glass vessel resting in a dish of water, and is filled with hydrogen mixed with a percentage of CO2. Inside the vessel a fragment of phosphorus is suspended, and as a small amount of oxygen is sure to be mixed with the hydrogen the phosphorus will be oxygenated and white fumes will fill the vessel. The observer must wait until these clouds have subsided, which may need a couple of hours. This must take place in the dark, and as soon as the atmosphere is clear, the whole preparation is placed in bright light, when obvious clouds will again appear--a proof that oxygen has been set free by the assimilation of the green plants. With this example I must bring my short series of experiments to a close, with the hope that my readers may not deny that they are picturesque.

XIV DOGS AND DOG LOVERS

"The more I see of men, the more I like dogs."--ARCHBISHOP WHATELY. {219}

Why is it that some people do not like dogs? There are those who dislike other people's dogs just as they dislike strange children. This is a point of view which is comprehensible though unattractive. Still, in comparison with those who do not like dogs at all this class seem positively amiable. I knew a lady with the most perfect understanding of the qualities of human beings, whether bad or good, yet she had no sympathy with dogs. She would be kind to them, as an external duty to all living things, but a dog had absolutely no place in her heart. What made this blindness seem all the more incomprehensible was the fact that she could love a bullfinch; she could not therefore plead that she loved humanity so much that she had no love left for beings of another sort. After all, it may be that not to care for dogs is no more a blemish than a lack of musical ear, which is not a sign of general dullness of artistic perception since it is found in some poets. We must accordingly allow that not to love dogs is not a sign of a black heart or a debased nature. A dog lover will grant this to be an unavoidable intellectual conclusion, but in the secret corners of his mind he will feel something more hostile than mere Christian pity for these emotionally deformed people. If he holds Erewhonian doctrines he would like to send for the family straightener, and bear with fortitude the punishment inflicted on his friends and relations.

I fear that we, the dog lovers, are, by those who do not share our tastes, held to be unbalanced persons, who intrude their passions on the reasonable and well bred. They object to us as victims of perverted instincts, who talk unknown dog-language in and out of season. It is not clear to me why we care so much for dogs. Is it, in truth, an exaggeration, or an offshoot of that love of the helpless young of our own kind which natural selection develops in social animals? This is not necessarily maternal, as we see in the story of the heroic male baboon, who risked his life in saving a young one from a pack of baying hounds. {220a} Or is it an instinct developed in a hunting tribe--a blind tendency to take good care of the food-providers (at the expense of starving aunts and grandmothers), such as we see among the Fuegians, who explained that, "Doggies catch otters--old women no." {220b}

However this may be, it is I think certain that the love of dogs is an unreasoning passion, having all the force of an instinct. In a story by Miss Wilkins we see how the love even of a cat may come to be regarded as a human right or need. The old woman who had lost her cat (he afterwards emerged half starved from the cellar), rebelled against the will of God. She allowed that the happiness of husband and children was possibly not to be expected by everyone, but "there _was_ cats enough to go all round."

I think it impossible to account for the especial affection that we bear to certain dogs. Dogs are, as I have said, in a degree like our children; they come to us and they have to be tended, fed, and guarded, and in these services we learn to love them. And when our affection is reflected back to us from the thing we love, it gains an especially touching quality. In the case of dogs our affection is certainly not a response to any inherent charm obvious to all the world--and here again they resemble children. The dog I loved best was an inferior Irish terrier, who gave me much trouble and anxiety. He was constantly fighting; he barked fiercely at innocent visitors. He killed chickens, and for this I had to beat him cruelly, tie him up and leave him trembling with a dead victim round his neck, a punishment for which I still feel remorse, though it saved him from being shot as a criminal, and cured him of his murderous tendency for many years. Pat was not a clever dog, and when striving to learn certain simple tricks he used to fall into abysses of miserable stupidity, and give up all hope of winning the biscuit earned by his fellow-dog, a Scotch terrier, with all the intelligent certainty of his nation. Pat had one attractive physical quality; he was perfectly sweet and clean; indeed his adoring family compared his scent to that of new mown hay; he had also a smooth head, which was compared, by one enthusiastic admirer, to a putting-green. He had the attractive and not very common quality of grinning--tucking up his lips and showing the teeth, but producing the effect of a smile, and expressing a shy and apologetic frame of mind.

Pat lived with a bad tempered Scotch terrier called Whisk, whom I liked for his strong character and intellectual acquirements, but I had no great affection for him. He could not bear being spoken to or even looked at while he ate his dinner, and would growl with his mouth full, in a terrific manner, if so disturbed. In the same ferocious spirit he would growl and snap if his basket was accidentally kicked when he was dozing in the evening, and however much we apologised he would take each expression of regret as a fresh insult, and answer them all with growls, which gradually died away in sleep.

We only once had a big dog, and he was not a success though he was an agreeable person. We bought him and his brother, two very fat mastiff puppies, at North Berwick, and brought them south. The one pleasant incident in the journey was the question of a German in Edinburgh station: "Madam, who are these dogs?" We gave away one and kept the other, who bore the magnificent name of Tantallon, soon abbreviated into Tan. He had many friendly habits, but they were on too large a scale for domestic life. He had, for instance, a way of placing a dirty paw on the table cloth at meals, and he knocked down street children by trying to lick their faces and (so rumour said) by wagging his tail. He frightened cab horses into hysterics, and their drivers fell off and claimed damages. He ate with enjoyment the embroidered perambulator-cushion of a neighbour, who was discovered looking on while Tan tore strips off the cushion with that powerful upward movement of the head and neck which few cushions can withstand. Finally poor Tan had to be given away, and was lost sight of.

These rough outlines of the characters of some of our dogs are meant to show that the reasons for loving dogs are not patent, and that we cannot complain if the words, used by a little girl in _Punch_ towards a couple of earwigs, should be applied to us and our dogs, "Nasty creatures! I cannot think how they can care for each other."