and thought of another man of genius fifty years before. The book of Malthus on the Principle of Population, mainly founded on the fact that animals increase in a geometrical ratio, and therefore, unchecked, must encumber the earth, had been generally forgotten, and was only recalled to remembrance now and then with a sneer. But the genius of Darwin recognized in it a deeper meaning, and now the thought of Malthus was joined to the new current. Meditating upon it in connection with his own observations of the luxuriance of Nature, Darwin arrived at his doctrine of natural selection and survival of the fittest.

As the great dogmatic barrier between the old and new views of the universe was broken down, the flood of new thought pouring over the world stimulated and nourished strong growths in every field of research and reasoning; edition after edition of the book was called for; it was translated even into Japanese and Hindustani; the stagnation of scientific thought, which Buckle only a few years before had so deeply lamented, gave place to a widespread and fruitful activity; masses of accumulated observations, which had seemed stale and unprofitable, were made alive; facts formerly without meaning now found their interpretation. Under this new influence a vast army of young men took up every line of scientific investigation in every land. Epoch-making books appeared in all the great nations. Spencer, Wallace, Huxley, Galton, Tyndall, Tylor, Lubbock, Bagehot, Lewes, in England, and a phalanx of strong men in Germany, Italy, France, and America gave forth works which became authoritative in every department of biology. If some of the older men in France held back, overawed perhaps by the authority of Cuvier, the younger and more vigorous pressed on.

One source of opposition in America deserves to be especially mentioned-Louis Agassiz.

A great investigator, an inspired and inspiring teacher, a noble man, he had received and elaborated a theory of animated creation which he could not readily change. In his heart and mind still prevailed the atmosphere of the little Swiss parsonage in which he was born, and his religious and moral nature, so beautiful to all who knew him, was especially repelled by sundry evolutionists, who, in their zeal as neophytes, made proclamations having a decidedly irreligious if not immoral bearing. In addition to this was the direction his thinking had received from Cuvier; both these influences combined to prevent his acceptance of the new view.

He was the third great man who had thrown his influence as a barrier across the current of evolutionary thought. Linnæus in the second half of the eighteenth century, Cuvier in the first half and Agassiz in the second half of the nineteenth-all made

the same effort. Each remains great; but not all of them together could arrest the current. Agassiz's strong efforts throughout the United States, and indeed throughout Europe, to check it, really promoted it. From the great museum which he had founded at Cambridge, from his summer school at Penikese, from his lecturerooms at Harvard and Cornell, his disciples went forth full of love and admiration for him, full of enthusiasm which he had aroused and into fields which he had indicated; but their powers, which he had aroused and strengthened, were devoted to developing the truth he failed to recognize; Shaler, Verrill, Packard, Hartt, Wilder, Jordan, and a multitude of others, and above all the son who bore his honored name, did justice to his memory by applying what they had received from him to research under inspiration of the new revelation.

Still another man deserves especial gratitude and honor in this great progress-Edward Livingston Youmans. He was perhaps the first in America to recognize the vast bearings of the truths presented by Darwin, Wallace, and Spencer. He became the apostle of these truths, sacrificing the brilliant career on which he had entered as a public lecturer, subordinating himself to the three leaders and giving himself to editorial drudgery in the stimulation of research and the announcement of results.

In support of the new doctrine came a world of new proofs; those which Darwin himself added in regard to the cross-fertilization of plants, and which he had adopted from embryology, led the way, and these were followed by the discoveries of Wallace, Bates, Huxley, Marsh, Cope, Leidy, Haeckel, Müller, Gaudry, and a multitude of others in all lands. The last theological efforts against these men we shall study in the next chapter.*

THE Royal Institution of Great Britain, in a memorial resolution to Professor Tyndall, adopted at a general meeting, speaks of him as one "who by his brilliant abilities and laborious researches nobly promoted the objects of the institution and conspicuously enhanced its reputation, while at the same time he extended scientific truth and rendered many new additions to natural knowledge practically available for the service of mankind."

*For Agassiz's opposition to evolution, see the Essay on Classification, vol. i, 1857, as regards Lamarck, and vol. iii, 1860, as regards Darwin; also Silliman's Journal, July, 1860; also the Atlantic Monthly, January, 1874; also his Life and Correspondence, vol. ii, p. 647; also Asa Gray, Scientific Papers, vol. ii, p. 484. A reminiscence of my own enables me to appreciate his deep ethical and religious feeling. I was passing the day with him at Nahant in 1868, consulting him regarding candidates for various scientific chairs at the newly established Cornell University, in which he took a deep interest. As we discussed one after another of the candidates he suddenly said: "Who is to be your Professor of Moral Philosophy? That is a far more important position than all the others."

THE GUESTS OF THE MAYFLOWER.

BY PROF. CLARENCE M. WEED.

No native plant has so endeared itself to the New England

heart as the mayflower. For two centuries it has been to old and young the sweetest of spring's harbingers as it pushed its dainty blossoms through the fallen leaves beside the lingering snow. It has charmed those fortunate ones who have wandered over the hills to find it, and has carried glad tidings to those compelled to stay at home. It has been constantly used to carry Cupid's message from youths to maidens-a custom which I like to fancy may have originated when, in the infancy of Plymouth, John Alden brought to Priscilla Mullens bunches of arbutus blossoms that spoke not only for themselves but also for the hand that plucked them.

But Epigaa is a plant of decided interest in itself apart from its associations. It was not originally designed as an emissary of

the goddess of love, and its beauty was primarily developed without reference to the æsthetic needs of the Pilgrims or their descendants. Long before the Mayflower reached Plymouth or Columbus landed at San Salvador-probably before the Indians arrived, and possibly before the glaciers came down from the north-the arbutus blossomed with each returning season and carried on the cycle of her existence as tranquilly as she does today. But her fragrance was by no means "wasted on the desert air," for she received then, as now, the tributes of a host of insect visitors that went about to do her unconscious bidding.

Although the trailing arbutus has been developing for so many centuries, it is still in a state of transition, and appears to be looking toward a goal which probably will not be fully reached

VOL. XLV.-2

for centuries to come. Every one with the least knowledge of the vegetable world knows that the great majority of flowering plants have the stamens and pistils in the same blossom, although Nature generally devises some method of preventing self-pollination. Many species, however, bear the pistillate blossoms on one plant or part of the plant, and the staminate blossoms on another plant or part of the plant, relying on insects or the wind to carry the pollen from the latter to the former. But occasionally there occurs a species whose flowers are neither wholly one nor the other, being in a transition stage between the two. In this category we find the mayflower.

The examination of the structure of a dozen bunches of arbutus blossoms reveals a great variation in the relative conditions and positions of the stamens and pistils. In some specimens the anthers are completely abortive; in others only partially so; and in others in good condition, well filled with pollen grains. Two types of stigmas are also present in some specimens the stigmas as a whole are broad and more or less flattened-spread out, so to speak-projecting at right angles to the style with the upper surface moist and glutinous; in others the stigmas are crowded into less space and project very little horizontally; they are drier and less glutinous, and evidently in a partially abortive condition. The perfect stigmas are usually associated with abortive anthers, and vice versa, so that many of the plants are already dioecious.

If the flowers are examined with reference to the length of the styles and filaments of the pistils and stamens, great variations will also be found. In some the stigmas are perfect and reach the mouth of the corolla; no anthers, and only rudiments of filaments are present. The variations I found on Blueberry Hill at Hanover, New Hampshire, may be epitomized as follows:

1. Stigmas perfect, reaching the mouth of the corolla; no anthers, and only rudiments of filaments present (Fig. 2, a).

2. Stigmas perfect, reaching the mouth of the corolla; anthers present, but abortive, reaching two thirds the way to the mouth. of the corolla (Fig. 2, b).

3. Stigmas perfect, reaching half way to the mouth of the corolla; anthers abortive or absent, not reaching the stigmas. 4. Stigmas imperfect, anthers perfect; both reaching the mouth of the corolla.

5. Stigmas imperfect, anthers perfect; both reaching two thirds of the way from the base to the mouth of the corolla.

6. Stigmas imperfect, reaching slightly beyond the mouth of the corolla; anthers perfect, reaching to the mouth (Fig. 2, c).

The relative proportions of the different forms seem to vary with the locality. The majority of specimens I have studied belonged either in the first or fourth category. The arbutus at Han

over is evidently tending strongly to a more perfect diœcism When it finishes its task of eliminating the filaments as it has the anthers of the stamens in many of the pistillate blossoms, and gets rid of the superfluous pistils of the staminate blossoms, it will accomplish its purposes of reproduction with less waste than at present.

A plant in the condition of the arbutus may be said to be in a certain sense at a "parting of the ways." To attain the end of cross-fertilization-the carrying of the pollen from the stamens of one plant to the pistils of another-two methods appear to be open to it. It may, and in the case of many of the Blueberry Hill specimens evidently has, become more perfectly dioecious by aborting the stamens on some plants and the pistils on others; or it might become dimorphous by developing perfect sexual organs

h

a

FIG. 2.-VARIATIONS OF THE MAYFLOWER.

in each blossom and having them at different heights-that is, having the stamens in one plant reach the mouth of the corolla and the pistil reach only half way to the mouth, while in another having the pistil long and the stamens short. The tendency toward dimorphism or trimorphism is shown by the varying lengths of the styles and filaments.

The blossoms of the common asparagus of our gardens show by their structure that they are in a transition stage somewhat similar to that of the arbutus. The staminate blossoms have rudimentary pistils and the pistillate blossoms rudimentary stamens, and sometimes a blossom is found which has both sets of organs in good condition-a reversion to an earlier condition of the plant.

The partridge berry,* a plant which has to contend with much the same external conditions as the arbutus, living in similar situations and remaining close to the ground, has adopted

*Michella repens.