depend, are merely quoted from a grander code applicable to all life in all times, your confidence in them will be even greater. I trust I can prove to you that the animal kingdom has not drifted aimlessly at the mercy of every wind and tide and current of circumstance. I hope to show that along one line it has from the beginning through the ages held a steady course straight onward, and that deviation from this course has always led to failure or degeneration. From so vast a history we may hope to deduce some of the great laws of true success in life. Furthermore, if along this central line, at the head of which man stands, there always has been progress, we cannot doubt that future progress will be as certain, and perhaps far more rapid. In all the struggle of life we shall have the sure hope of success and victory; if not for ourselves still for those who shall come after us. "We are saved by hope." And we may be confident that this hope will never make us ashamed.

Finally, even from our present knowledge of the past progress of life we shall hope to catch hints at least that man's only path to his destined goal is the straight and narrow road pointed out in the Bible. If in this we are even fairly successful we shall find a relation and bond between the Bible and Science worthy of all consideration. And this is the only agreement which can ever satisfy us.

If I wished to bring before you a view of the development of man, I should best choose individuals or families from various periods of human history from the earliest times down to the present. I should try to tell you how they looked and lived. But if anyone should attempt to condense into three lectures such a history of even one line of the human race, you would probably think him insane. Even if he succeeded in giving a fairly clear view of the different stages, the successive stages would be so remote from one another, such vast changes would necessarily remain unnoticed or unexplained that you would hardly believe that they could have any genetic relation or belong to one developmental series.

But the history which I must attempt to condense for you is measured by ages, and the successive terms of the series will be indefinitely more remote from each other than the life and thoughts of Lincoln or Washington from those of our most primitive Aryan ancestor or of the rudest savage of the Stone Age. The series must appear exceedingly disconnected. Systems of organs will apparently spring suddenly into existence, and we shall have no time to trace their origin or earlier development. Even if we had an abundance of time many gaps would still remain; for the forms, which according to our theory must have occupied their place, have long since disappeared and left no trace nor sign. We have generally no conception at all of the amount of extermination and degeneration which have taken place in past ages.

I grant frankly that I do not believe that the forms which I have selected represent exactly the ancestors of man. They have all been more or less modified. I claim only that in the balance and relative development of their organic systems—muscular, digestive, nervous, etc.—they give us a very fair idea of what our ancestor at each stage must have been. But it is on this balance and relative development of the different systems, that is, whether an animal is more reproductive, digestive, or nervous, that my argument will in the main be based.

But if the older ancestors have so generally disappeared, and their surviving relatives have been so greatly modified, how can we make even a shrewd guess at the ancestry of higher forms? The genealogy of the animal kingdom has been really the study of centuries, although the earlier zoölogists did not know that this was to be the result of their labors. The first work of the naturalist was necessarily to classify the plants and animals which he found, and catalogue and tabulate them so that they might be easily recognized, and that later discovered forms might readily find a place in the system. Hypotheses and theories were looked upon with suspicion. "Even Linnæus," says Romanes, "was express in his limitations of true scientific work in natural history to the collecting and arranging of species of plants and animals." The question, "What is it?" came first; then, "How did it come to be what it is?" We are just awakening to the question, "Why this progressive system of forms, and what does it all mean?"

Let us experiment a little in forming our own classification of a few vertebrates. We see a bat flying through the air. We mistake it for a bird. But a glance at it shows that it is a mammal. It is covered with hair. It has fore and hind legs. Its wings are membranes stretched between the fingers and along the sides of the body. It has teeth. It suckles its young. In all these respects it differs from birds. It differs from mammals only in its wings. But we remember that flying squirrels have a membrane stretching along the sides of the body and serving as a parachute, though not as wings. We naturally consider the wings as a sort of after-thought superinduced on the mammalian structure. We do not hesitate to call it a mammal.

The whale makes us more trouble; it certainly looks remarkably like a fish. But the fin of its tail is horizontal, not vertical. Its front flippers differ altogether from the corresponding fins of fish; their bones are the same as those occurring in the forelegs of mammals, only shorter and more crowded together. Later we find that it has lungs, and a heart with four chambers instead of only two, as in fish. The vertebræ of its backbone are not biconcave, but flat in front and behind. And, finally, we discover that it suckles its young. It, too, is in all its deep-seated characteristics a mammal. It is fish-like only in characteristics which it might easily have acquired in adaptation to its aquatic life. And there are other aquatic mammals, like the seals, in which these characteristics are much less marked. Their adaptation has evidently not gone so far.

Now the first attempts resulted in artificial classifications, much like our grouping of bats with birds and whales with fish. All animals, like coral animals and starfishes, whose similar parts were arranged in lines radiating from a centre, were united as radiates, however much they might differ in internal structure and grade of organization. But this radiate structure proved again to be largely a matter of adaptation.

Practically all animals having a heavy calcareous shell were grouped with the snails and oysters as mollusks. But the barnacle did not fit well with other mollusks. Its shell was entirely different. It had several pairs of legs; and no mollusk has legs. The barnacle is evidently a sessile crab or better crustacean. Its molluscan characteristics were only skin-deep, evidently an adaptation to a mode of life like that of mollusks. The old artificial systems were based too much on merely external characteristics, the results of adaptation. When the internal anatomy had been thoroughly studied their groups had to be rearranged.

Reptiles and amphibia were at first united in one class because of their resemblance in external form. Our common salamanders look so much like lizards that they generally pass by this name. But the young salamander, like all amphibia, breathes by gills, its skeleton differs greatly from, and is far weaker than, that of the lizard, and there are important differences in the circulatory and other systems. Moreover, practically all amphibia differ from all reptiles in these respects. Evidently the fact that the alligator and many snakes and turtles (of which neither the young nor the embryos ever breathe by gills) live almost entirely in the water, is no better reason for classifying