thousand years could not be done by pope and prelate in Ireland is done here in a few months by widened mental environments. Structures abject and brutish, in the next generation rise up to dignity; and with the body stands up the soul. This is the law of development. The world is gloriously full of its illustrations.

I shall close this lecture by showing you how Nature, as if to clinch the argument, often leaps back in her forms; or, as we say, reverts. This is when the power of heredity is stronger than the environments. I had a flock of Plymouth Rock fowls. Most of them have black chickens. One progenitor of this breed is the Black Java, and heredity is very strong to carry the whole stock back to an original type. The environments to sustain the new strain must be carefully looked after. I told you in a previous lecture of the difficulty I meet in fixing any one of several hundred cross-bred beans so that they shall not either revert, or the environments produce new crosses.

When we find a child born with the features of a grandfather, or some of his peculiarities, we say it is a case where heredity draws so strongly as to make the individual revert. A lady met me in your streets the other day who had serious trouble with her boy. I said, "Why don't you whip the rogue?" She replied, with great wisdom, "Would you have me try to whip his grandfather?" He has inherited a propensity; it is not free choice. This was a case of mental reversion. And in modern morals there is no more important consideration than this of heredity. No one can begin to comprehend his duty as a reformer, a parent, or a teacher, who does not comprehend the power of the mind and manners to jump back to an ancestral copy. The evil and the good in us is ours; but it is often a sharply outlined copy from our parents.

Our structures are in reality always so strongly subject to the family bias that more or less of reversion occurs. The strongly marked cases are the result of heredity itself cre

ating environments. I have a friend whose hands and feet are composed of flaps, somewhat like those of a seal. A sac incloses a rudiment of a hand, and with this he writes and works, and has achieved a high position. This is an inheritance of several generations, and belongs to other lateral members of the family. Environment does not easily get rid of such cases, because a malformation is itself an ever-present influence. But reversion proper is wider than common inheritance. It is leaping over one, two, or many generations. A case of double womb occurring in an animal of high rank is a leap as far back as the beginning of the mammals. The very first of the milk-givers gave birth to their young prematurely, placing them thereafter in an external womb, or pouch. The young of a kangaroo, when it leaves the internal womb, is only about an inch long, and resembles a worm; but in the external womb it is slowly developed and nourished till able to go alone. This double womb occasionally occurs in a creature of much higher rank. Nor is the occasional appearance of tails in human beings anything but reversion of type. The heredity is in all of us that includes the animal tail, as well as other structural parts aborted. As a rule, these possible appendages are rehearsed and left behind in the embryo development; but occasionally they are not dropped at all but cling to us through adult life. The law is verifiable, however, that every variation from the normal human type is a variation toward some preceding animal form—no abnormality is ever a pure freak toward a new sort of organic appendage. For instance, a muscle occasionally occurs reaching from the hip-bone to the abdomen; it is the muscle which constitutes the second, external, or double womb to which I have referred. Occasionally a rib is adjoined to the neck vertebræ; that is reversion to the bird type. The tail, when it occurs, is a reversion to the monkey type. But no variation occurs which is not a reversion.

If the believer in special creations answers that a power

exists in Nature to create new organs, and therefore these are not cases of reversion at all, he thereby allows to Nature creative power of a very direct and wonderful sort much so that he destroys the argument for any Final Cause; for if Nature can make one organ she can make two, or more, and by parity of reasoning a whole creature. Of course, the antagonists of evolution can take as often as they like their stand at the cross-road of species, and aver that all this interchange of structure goes on within certain limits-that it never crosses the line of species. It is, however, a merely imaginary line, established arbitrarily, and there are abundant reasons for believing that practically there are no such limits and bounds, as I have before explained. Mr. Darwin found among his pigeons cases of reversal that connected his nestlings with a type that certainly went out of existence as long ago as 1676, over two hundred years. Not long since a gentleman, now in this audience, related to me a case of a two-toed horse. This was atavism or reversion, connecting the creature with the pre-historic ancestor, of the Tertiary period, that was normally two-toed. The last point at which the inheritance of the horse was fastened was the foot; and from that point it most readily reverts.

I have said enough of the bearing of this topic of development and reversion to show you its bearing on our condition as rational and responsible creatures. Evolution furnishes a basis for morals as wide as the history of life itself. From it must follow not a collapse of our moral sentiment, and a degradation of worship, but an elevation of the ideal to be worshiped; and a nobler conception of what we ought to be, and to do. We are all interlinked in origin, in life, in destiny. The end of morality is not a selfish paradise, but that heaven that consists in ennobling and helping the damned. The eye that can weep over a neighbor's sorrow has been at last evolved, but with it has been developed the hand that can help to relieve his bur

den. So Nature emerges from her lowly state, and, seated on a throne in the human brain, bids us

"Work out the beast, and let the ape and tiger die."

Unfortunately, atavism is neither rare nor difficult, and our social life is seriously burdened with it.

LECTURE VII.

THE POWER OF MIMICRY.

WALKING through the edge of my aftermath the other day, I came upon a little brown game hen who had stolen a nest by the side of a huge bunch of tufted grass. I had hunted for her, and probably seen her before, but this time she did not deceive me. Motionless she sat, with only those sharp eyes intent on me. Her brown color fitted admirably to the brown soil and grass, and to it she pressed close, leaving the green tufts to wave over her. I went carefully close to her and touched her, when she noiselessly slid away into the taller cover. It was a case of conscious protection by imitation. The hen knew that a motion would betray her, and made none. It is clear that among wild fowl those that are most like in color to their surroundings will be most sure to escape their enemies and propagate their families. Did you ever find a bobolink's nest? If you have, you know how exactly the little lady fits to the nest and its surroundings in color, while the gay partner sails away in bright colors, that on the nest would be detected at once. This you will find to be a universal fact, to be observed readily in any direction, that birds liable to be preyed upon are inconspicuous in the female sex; while those that are fearless and predatory, like crows, do not vary in the color of the sexes. The crow has no reason for ever concealing itself, for its food is mostly dead matter, and it is itself not sought for food. The law of selective