for his experiments. Those on the movements of stems and roots were still in progress. The hours passed like minutes. I had to leave. Precious memories of that visit remain."

Yet once more, in 1881, the famous publishing house of Murray issued a new work-his last-by the great illuminator of Nature. Its subject was one which no one save those who knew him could have expected. It dealt with "The Formation of Vegetable Mould, through the Action of Worms, with Observations on their Habits," and in it the lowly earthworm was at last raised to its true rank as the genuine preparer and possessor of the soil. Both Gilbert White and Edward Jenner had been impressed with the work earthworms do in nature, but no one had written extensively on the subject till Darwin himself, in 1837, read a short paper on the "Formation of Mould" before the Geological Society of London (published in the fifth volume of the Society's Transactions), showing that small fragments of burnt marl, cinders, &c., which had been thickly strewed over the surface of several meadows, were found after a few years lying at the depth of some inches beneath the turf. It was suggested to him by his relative Mr. Wedgwood, of Maer Hall, in Staffordshire, that this was due to the quantity of fine earth continually brought up to the surface by worms in the form of castings. Observation and experiment were to settle the question in the usual Darwinian manner, and many a portion of soil was watched. One experiment lasted nearly thirty years, for a quantity of broken chalk and sifted coal

cinders was spread on December 20, 1842, over distinct parts of a field near Down House, which had existed as pasture for a very long time. At the end of November, 1871, a trench was dug across this part of the field, and the nodules of chalk were found buried seven inches. A similar change took place in a field covered with flints, where in thirty years the turf was compact without any stones. A pathway formed of loose-set flagstones was similarly buried by worms, and became undistinguishable from the rest of the lawn. And these are but a few of the evidences of the wonderful action of worms, collected by the activity of Charles Darwin and his sons.

Earthworms were not only scrutinised in their out-ofdoor work, but were kept in confinement and studied. It appears they swallow earth both to make their burrows and to extract all nutriment it may contain; they will eat almost anything they can get their skin over. From careful calculation it was shown that worms on an average pass ten tons of the soil on an acre of ground through their bodies every year. It is, then, but a truism to say that every bit of soil on the surface of the globe must have passed through their bodies many times. They were discovered to work mainly by night, when hundreds may with care be discerned, with tails fixed in their burrows, prowling round in circles, rapidly retreating into holes, and strongly resisting efforts to extract them. It was found by careful study that they have no sense of hearing, but a most remarkable sensitiveness to vibrations of the earth or even to contact with air in motion. No book Darwin wrote was fuller of interesting and undoubtedly correct observations.

In concluding, the author enforces the claims of worms on the gratitude of archæologists, as they protect and preserve for an indefinitely long period every object not liable to decay which is dropped on the surface of the land, by burying it beneath their castings. It is thus that many tesselated pavements and other ancient remains have been preserved; but, on the other hand, worms have undermined many old massive walls and caused them to subside, and no building is in this respect safe unless the foundations are at least six or seven feet beneath the surface, below which depth worms cannot work. Worms also prepare the ground in an excellent manner for plant life, periodically exposing the mould to the air, sifting it so that no stones larger than the particles they can swallow are left in it, mingling the whole intimately together, burying all decaying objects within reach of the roots of the plants, allowing air to penetrate deeply into the earth. "When we behold a wide, turf-covered expanse, we should remember that its smoothness, on which so much of its beauty depends, is mainly due to all the inequalities having been slowly levelled by worms. It is a marvellous reflection that the whole of the superficial mould over any such expanse has passed, and will again pass, every few years through the bodies of worms. The plough is one of the most ancient and most valuable of man's inventions; but long before he existed the land was in fact regularly ploughed, and still continues to be thus ploughed by earthworms. It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organised creatures."

After this last book Darwin felt much exhausted, and wrote: "I feel so worn out that I do not suppose I shall ever again give reviewers trouble." His brother Erasmus's death in the same year was the severance of a link with early days. Yet for some months he continued in a moderate degree of health, still working. For some weeks however in the following March and April he was slightly unwell, and the action of his heart became so weak that he was not allowed to mount the stairs. On Tuesday, April 18, he was in his study examining a plant which he had had brought to him, and he read the same evening before retiring. Till the day of his death he did not become seriously ill. On that day the heart, which had so long done its duty, failed, and about 4 p.m., on April 19, 1882, Charles Darwin breathed his last in peace, aged seventy-three years, two months, and seven days.

CHAPTER XI.

HE death of Charles Darwin focussed, as it were,

THE

into one concentrated glow the feelings of admiration, and even reverence, which had been growing stronger and stronger in the years since the "Origin of Species" was published. It soon became evident that a public funeral in Westminster Abbey was very generally called for, and this being granted, a grave was chosen in the north aisle and north-east corner of the nave, north of and side by side with that of Sir John Herschel, and ten or twelve feet only from that of Sir Isaac Newton. On April 26, 1882, a great representative host of scientists, literary men, politicians, and theologians assembled for the final scene. The pallbearers were the Dukes of Devonshire and Argyll, the Earl of Derby, Mr. J. Russell Lowell (then American Minister in London), Mr. W. Spottiswoode (President of the Royal Society), Sir Joseph Hooker, Mr. Alfred Russel Wallace, Professor Huxley, Sir John Lubbock, and Canon Farrar. The Bishop of Carlisle, preaching at the Abbey on the following Sunday, admitted that Darwin had produced a greater change in the current of thought than any other man, and had done it by per