18 THE WHENCE AND THE WHITHER OF MAN 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.

anyone

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 a 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 I could have any genetic relation or belong to one developmental series.

for you

But the history which I must attempt to condense
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 Wash-
ington from those of our most primitive Aryan ances-
tor or of the rudest savage of the Stone Age. The
series must appear exceedingly disconnected. Systems
of organs will apparently spring suddenly into exist-
ence, 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. 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 it is on

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 "Even Linnæus," says with suspicion. 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 tion, "What is it?" came first; then, "How did it come to be what it is?" We are just awakening to the ques

looked upon

ques

66

does it all mean?"

Let

20 THE WHENCE AND THE WHITHER OF MAN Why this progressive system of forms, and what experiment a little in forming our own classification of a few vertebrates. We see a bat flying glance at it shows that it is a mammal. It is covered through the air. We mistake it for a bird. But a with hair. It has fore and hind legs. Its wings are

the sides of the body.

It has teeth. It suckles its

young. In all these respects it differs from birds. It member that flying squirrels have a membrane stretchchute, 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

The whale makes us more trouble; it certainly looks

remarkably like a fish. But the fin of its tail is hori-
zontal, 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 y
too, is in all its deep-seated characteristics a mammal.
It is fish-like only in characteristics which it might eas-
ily have acquired in adaptation to its aquatic life. And
other aquatic mammals, like the seals, in
which these characteristics are much less marked.
Their adaptation has evidently not gone so far.

there

are

young. It,

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.

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, practiIcally 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

22 THE WHENCE AND

these with

THE WHITHER OF MAN

amphibia than to call a whale a fish, and

When the comparative

anatomy of fish, amphibia,

not a mammal, because of its form and aquatic life. and reptiles had been carefully studied it was evident structure, while the higher reptiles closely approached that the amphibia stood far nearer the fish in general

birds.

Then it was

noticed that our common fish

formed a fairly well-defined

group, but that the ganoids,

including the sturgeons, gar-pikes, and some others, had at least traces of amphibian characteristics. Such

less sharply marked,

were usually by common consent

placed at the bottom of the class. And this suited acteristics they were often more highly organized than well their general structure, while in particular charThe paleontologist found that the oldest fossil forms

higher groups of the same

belonged to these generalized

groups, and that more

highly specialized forms—that is, those in which the special class distinctions were more sharply and universally marked-were of later geological origin. Thus the oldest fish were most like our present ganoids and sharks, though differing much from both. Our common teleost fish, like perch and cod, appeared much later. The oldest bird, the archaeopteryx, had a long tail like that of a lizard, and teeth; and thus stood in many respects almost midway between birds and reptiles. And most of the earliest forms were "comprehensive," uniting the characteristics of two or more Thus as the classification became more natural, based on a careful comparison of the whole anatomy of the animals, its order was found to coincide in general with that of geological succession.

later

groups.