It makes its verdict much as the judges at a great poultry or dog show count the series of points, giving each one of them a certain value on a certain scale, and then award the prize to the individual having the highest aggregate on the whole series. Any such illustration is very liable to mislead; I wish to emphasize that fitness to survive is determined by the aggregate of the qualities of an individual.

But an animal having one organ of great value or capacity may thus carry off the prize, even though its other organs deserve a much lower mark. This is the case with man. In almost every respect, except in brain and hand, he is surpassed by the carnivora, the cat, for example. But muscle may be marked, in making up the aggregate, on a scale of 500, and brain on a scale of 5,000, or perhaps of 50,000. A very slight difference in brain capacity outweighs a great superiority in muscle in the struggle between man and the carnivora, or between man and man.

The scale on which an organ is marked will be proportional to its usefulness under the conditions given at a given time. During the period of development of worms and lower vertebrates much muscle with a little brain was more useful than more brain with less muscle. Hence, as a rule, the more muscular survived; the brain increasing slowly, at first apparently largely because of its correlation with muscle and senseorgans. At a later date muscle, tooth, and claw were more useful on the ground; brain and hand in the trees. Hence carnivora ruled the ground, and certain arboreal apes became continually more anthropoid. At a later date brain became more useful even on the ground, and was marked on a higher scale, because it

could invent traps and weapons against which muscle was of little avail. Just at present brain is of use to, and valued by, a large portion of society in proportion to its efficiency in making and selfishly spending money. But slowly and surely it is becoming of use as an organ of thought, for the sake of the truth which it can discover and incarnate.

Natural selection works thus apparently for the survival of the individuals possessing in the aggregate the most complete conformity to environment. Let us now imagine that an animal is so constructed as to be capable of variation along several disadvantageous or neutral lines, and along only one which is advantageous. The development would of course proceed along the advantageous line. Let us farther imagine that to the descendants of this individual two, and only two, advantageous lines of variations are allowed by its structure. Then natural selection would probably favor the decidedly advantageous line, if such there were. But as long as the structure of the animal allows variation along only a few lines, the two advantageous variations would, according to the law of probabilities, frequently occur in the same individual. The eggs and spermatozoa of two such individuals might not infrequently unite, and thus in time the two characteristics be inherited by a large fraction of the species.

And now let me quote from Mr. Spencer :

"But in proportion as the life grows complex-in proportion as a healthy existence cannot be secured by a large endowment of some one power, but demands many powers; in the same proportion do there arise obstacles to the increase of any particular power, by the preservation of favored races in the

struggle for life.' As fast as the faculties are multiplied, so fast does it become possible for the several members of a species to have various kinds of superiorities over one another. While one saves its life by higher speed, another does the like by clearer vision, another by keener scent, another by quicker hearing, another by greater strength, another by unusual power of enduring cold or hunger, another by special sagacity, another by special timidity, another by special courage; and others by other bodily and mental attributes. Now it is unquestionably true that, other things equal, each of these attributes, giving its possessor an extra chance of life, is likely to be transmitted to posterity. But there seems no reason to suppose that it will be increased in subsequent generations by natural selection. That it may be thus increased, the individuals not possessing more than average endowments of it must be more frequently killed off than individuals highly endowed with it; and this can happen only when the attribute is one of greater importance, for the time being, than most of the other attributes. If those members of the species which have but ordinary shares of it, nevertheless survive by virtue of other superiorities which they severally possess, then it is not easy to see how this particular attribute can be developed by natural selection in subsequent generations. The probability seems rather to be that, by gamogenesis, this extra endowment will, on the average, be diminished in posterity-just serving in the long run to compensate the deficient endowments of other individuals whose special powers lie in other directions, and so to keep up the normal structure of the species. The working out of the process is here somewhat difficult to follow; but it appears to me that as fast as the number of bodily and mental faculties increases, and as fast as the maintenance of life comes to depend less on the amount of any one, and more on the combined action of all, so fast does the production of specialties of character by natural selection alone become difficult. Particularly does this seem to be so with a species so multitudinous in its powers as mankind, and above all does it seem to be so with such of the human powers as have but minor shares in aiding the struggle for life-the aesthetic faculties for example."-Spencer, "Principles of Biology," ? 166.

Can thus natural selection, acting upon fortuitous variations, be the sole guiding process concerned in progress? Must there not be some combining power to produce the higher individuals which are prerequisites to the working of natural selection?

We are considering the efficiency of natural selection in enhancing useful variations through a series of generations. Let us return to the distinction between productiveness and prospectiveness of social capital. Applied to variations productiveness means immediate advantage, prospectiveness the greater future and permanent returns. Now all persisting variations must, in animals below man, apparently be somewhat productive, else they would not continue, much less increase. Now the immediate return from prospective variations is often smaller than from productive. It looks at first as if productive variations would always be preserved by natural selection, and that prospective variations would not long advance. Yet in the muscular system variations valuable largely for their future value are neither few nor unimportant. How can the brain in its infancy develop until it gains supremacy over muscle, or muscle have done the same with digestion? Now a partial explanation of this is to be found in the correlation of organs. This is therefore a factor of vast importance in progress through evolution.

Progress in any one line demands correlated changes in many organs. Thus in the advance of annelids to insects the muscular system increases in relative bulk, and absolutely in complexity. But a change or increase in the muscle must be accompanied by corresponding changes in the motor-nerve fibrils; and these

again would be useless unless accompanied by increased complexity and more or less readjustment of the cells and fibrils of the nerve-centres. And all these additions to, and readjustments of, the nervecentres must take place without any disturbance of the other necessary adjustments already attained. This is no simple problem.

We will here neglect the fact that many other changes are going on simultaneously. Legs are being formed or moulded into jaws, the anterior segments are fusing into a head, and their ganglia into a brain; an external skeleton is developing. Furthermore the increase of the muscular and nervous systems must be accompanied by increased powers of digestion, respiration, and excretion. Practically the whole body is being recast. We insist only on the necessity of simultaneous and parallel changes in muscles, nerves, and nerve-centres; though what is true of these is true, in greater or less degree, of all the other organs.

You may answer that this is to be explained by the law of correlation of organs; that when changes in one organ demand corresponding changes in another, these two change similarly and more or less at the same time and rate. But this is evidently not an explanation but a restatement of the fact. The question remains, What makes the organs vary simultaneously so as to always correspond to each other? The whole series of changes must to some extent be effected at once and in the same individual, if it is to be preserved by natural selection. Fortuitous variations here and there along the line of the series are of little or no avail. That the whole series of variations should happen to occur in one animal is altogether