CHAPTER V.

MAN'S PHYSICAL PLACE IN NATURE.

WE ex

E have now reached a point where matter extraneous to the subject, constantly obstructing its fair discussion, having been put aside, we can dispassionately examine the question involved. The only remaining difficulty to be encountered in discussing it is one which, owing to the constitution of the mind, is unavoidable in the examination of any new proposition. The mind, while searching for truth, and eagerly imbibing it (desire to know the truth being, as John Stuart Mill thought, the dominant characteristic of mankind), is nevertheless strongly conservative in its tendencies. For proof, one has but to look around to see how at the mercy of circumstances most conviction is. The savage implicitly takes upon credit what he inherits in belief from his progenitors. So he goes on, generation after generation, making no advance. The civilized man, too, but with a difference to be presently noted, believes what is transmitted to him, because he, equally with the savage, must accept the main stock of beliefs presented to him, for it would be as irrational in his case as in that of the savage for him to reject that which there is nothing to replace, and for each individual thus to begin the world afresh, and because, from the beginning to the end of life, as no one can learn everything for himself, he is perforce obliged mainly to accept as true that which he finds at hand.

Thus we see among men manners which they inherit, religion which they inherit, and knowledge of nature which they inherit. But there is this important difference between the civilized and the savage man, that the mind of the former has become more plastic than that of the other. He is open to conviction on subjects in which his senses belie the facts. He knows that the

senses alone are most fallible in their conclusions. He uses them only as avenues by which impressions reach him, and he summons them as witnesses to testify before his intellect, to contradict or confirm each other, and thereby make manifest the truth. On the contrary, the crucial test of the savage is a single one, the visual test. With him seeing is believing. He is unequal to the conception that seeing may be illusory. So also, and for the same reason, it is to be observed in the uneducated, among civilized beings, that seeing is the final test of right to believe.

The educated, although they do, as admitted, possess a stock of inherited beliefs, differ in sum from the savage and the uneducated among the civilized in the important points, that they are perfectly aware that a portion of their stock of beliefs must, from the nature of things, be erroneous, that they are distrustful of their powers of reaching truth, and that they are consequently careful in arriving at conviction. This attitude of mind is the only sure foundation for advance. The world can advance on no other terms. The modern investigation into the nature which we see all around us is, as was the ancient, with most imperfect means, prompted by an inherent desire to know and to abide by the truth. The prompting has been called scientific wonder, which term truly designates the feeling with which men approach the mysteries of nature. To suppose that it is not associated in the majority of the ablest minds with a reverential attitude is to be ignorant of the glories that are unfolded, and of the effect of their contemplation.

Love of the truth, from the lowest savage, from the virago of civilization who, standing with arms akimbo, listens to gossip about her neighbors, to the one who lives in the world of microscopic beings as well as in his own, or the one who sits observant of the marshalling of the stars, is a distinctively human attribute, capable, as these extremes show, of infinite development for

good. It is developed love of truth which is leading the present great advance of civilization in science, literature, and the arts. It is this prompting which has led to investigation of the genealogy of man, the sources of his earthly being.

When we survey the whole animal world a most remarkable series of facts present themselves. We find individual life bound up in a single cell, in colonies of cells, in animals composed of a few cells, and in those composed of multitudinous cells. We find cells in the same animal producing tissue, and, while so producing, changing their forms to suit special purposes. We find in the human organism, for instance, excluding the primary, and from the first, somewhat differentiated cell called the ovum, or egg, cells which seem capable of infinite differentiation, to form bone, marrow, skin, and all other parts of the body.

Passing beyond these phenomena, we find in all the animal kingdoms strange similarities, masked by dissimilarities, of structure as representing function. We find, referring now only to the vertebrates, that even skull and brain seem to be graduated from vertebræ, one of the lowest, if not the very lowest of the vertebrates, the lancelet (amphioxus), which was classed by Cuvier as a worm, being without a head.

But now, confining ourselves strictly to the vertebrate subkingdom, lest we become involved in considerations too extended for our purpose, it is to be remarked that we find among them a distinct graduation among organs. Just as before we saw that, comparing living with 'extinct forms, there is reason to believe that among animals there has been a continuous related transla tion of one form into another, these branching off at times from some common progenitors into separate lines of descent; so, also, we find, among vertebrates, external and internal differences of structure relating to function, which seem to graduate into each other. More than that, when we come to examine at different periods of its development the embryo of the same

animal, we find singular attributes to be possessed by it apparently unnecessary to its present or prospective existence.

That all things which are known to us should present in every respect conditions the object of which is manifest, is an untenable proposition. But that all things which are known to us should not present contradictions between the main conditions observed and the main purposes of life to be subserved, is a perfectly tenable proposition, for, when there is a contradiction be. tween those main conditions and the main purposes of the individual life, we reject those things which are in opposition to the main purposes of life, as having no relation to it. The dewclaw of the dog is not only not of service to the animal, but is of positive disservice to him, being frequently injured and causing him uneasiness. We therefore reject it as having any adapted relation to his present life, and recognize it as a rudiment of what was originally useful.

Now, the human embryo, the foetus, does not respire through the lungs. It could not breathe through its lungs, because it is submerged in a fluid called the liquor amnii until, the period of gestation being past, birth begins. The first respiration which the newborn child makes is accompanied by a sneeze or a cry, showing the unwonted impact of air upon the lungs. It respires, as do all placental mammals, or those animals which have a placenta and suckle their young. The placenta, a vascular, temporary organ (the after-birth), conveys to the fœtus, through the umbilical cord, circulation derived from the mother, involv ing the oxygenation of its blood and the removal from it of effete matters. The umbilical cord, containing the proper arteries and veins, which cord directly connects the unborn child with the placenta, is the only means by which circulation, respiration, and nutrition are effected in the unborn child by the circulation of the mother.

Beginning with the mother herself, we see, through embry