Variation.—What is even more surprising in biology, however, is that there is another marvelous force at work quite as incomprehensible in its way, perhaps even more so, than that of heredity. This is variation. All creatures have a tendency to vary from their parents. A very small proportion of the offspring resemble parents so closely as to be quite similar. The great majority of them, however, have noteworthy, individual, distinctive qualities. Occasionally these qualities may be traced to the less immediate ancestors and then we talk about reversion. Occasionally there appears in a child some trait or anomaly supposed to be remotely ancestral and it is spoken of as atavism. Whenever there is a tendency of the offspring of exceptional parents to regress toward the racial average, we talk of regression. Tall parents often have tall children, some of them may, by a special tendency of heredity, be taller even than themselves. Most of them will be shorter, however, and tend to regress toward the racial average.

Few people understand what a wonderful power among living things is exerted by this very opposite of heredity—variation. All the possibility of improvement not only in humanity but among all living things is dependent on variation. It does not seem difficult to understand how offspring resemble parents. They are of them, therefore they are like them. When we analyze the problem of heredity, however, and find that the connecting link between offspring and parents is always only a single cell of less than one one-hundredth of an inch in diameter, the mystery of heredity looms up in all its immensity. This minute bit of protoplasm, so small that it requires a rather strong power of the microscope to see it, somehow contains compressed within itself all the qualities that characterize the parent and are to be transmitted to the offspring. Among animals, the color of the eyes and hairy covering, the form and height of the animal, its generic characteristics, and its individual characters—all are contained within this minute spherule. The white blaze on the horse's hind leg, the black blotch on the puppy's face, the white lock on a human head, are all carried over from one generation to another with all the other qualities in this small package. That is the mystery of heredity.

To this must be added another mystery quite as great and even more [{634}] difficult to understand—variation. This tendency to vary is the basis for whatever evolution there is in the world. Some living things vary in such a way as to be better suited to their environment than they were before and then these outlive others because more favorably situated, and natural selection brings about a maintenance of the favorable variation. Instead, then, of patients being impressed with the unfavorable influence of heredity, they should rather be made to feel the weight of the idea that whatever evil tendencies the parent has the child is more likely to have less of them than more, so that variation tends to make the race better. We have had too much stress laid on the heredity of unfortunate qualities and entirely too little made of the variation tendency, which is constantly lifting the race up. It is, of course, only what happens in everything else, unfavorable are likely to have more weight than favorable suggestions, and unless these latter are emphasized their influence becomes swamped. This has happened with regard to variation. It is quite as important a biological element as heredity and it makes for the removal of unfortunate qualities, yet it has never become a popular idea and is little appreciated even by physicians.

Patients who are worried about their heredity will, after a frank discussion of our present knowledge of heredity and its co-ordinate factor of variation, lose most of their dread of this specter of supposed evil influence which so often proves the source of discouragement and failure to react properly against pathological conditions. There is probably no phase of modern biology in which the so-called popularization of science has done more harm by providing an abundant source ol unfortunate suggestions. Whatever influence heredity has in relation to disease is favorable to the human race. It is true that this is exerted by the elimination of the unfit, yet the very consequence of this is that the children of parents who have suffered from a particular disease are likely to have greater average resistance to it than the generality of mankind, since their parents passed the age up to reproductive activity without succumbing to it. For cancer, tuberculosis and syphilis this teaching is of special value and is probably more effective than any other single means could be to prevent the ravages of the disease if it should occur, since it keeps the patient from interfering with his own resistive vitality by the discouraging conviction that there is no possible hope for him because his parents also suffered from the disease.

CHAPTER V
PREMONITIONS

A state of mind that disturbs many people seriously, sometimes even producing physical results, because of the burden of dread that hangs over them, is that in which attention is paid to premonitions of evil. There are two of these general conditions to be considered. In the one there is a definite feeling that some special evil, occasionally very particularly outlined in the mind, as a railroad accident, fire, or a street accident of some kind, is to occur. In another mental condition there is a generic premonition of evil, [{635}] as if the worst were sure to happen and the patients must be constantly preparing for it. Occasionally this takes on some such form as an assurance of early breakdown in health, or of death at an untimely age, or of some crippling infirmity. This represents, of course, only one form of lack of control over the mind, but it is surprising how much physical suffering it may occasion. Only those who have had much to do with patients who suffer from this state of mind realize it. Sympathetic knowledge of the conditions that bring it about and of the real significance of premonitions will do more to help patients than anything else.

Every now and then newspapers tell the story of someone who had an impending sense of danger, perhaps of a particular form of accident or misfortune, which he could not shake off and which finally came true. Sometimes it is a fire that was anticipated, though without any reason except the dread, and precautions that eventually proved life-saving to the patient were taken, or at least friends were told of it so that the person seemed actually to have had some warning beforehand of the danger that was to come. Sometimes it is the story of a railroad accident, which some particularly fortunate individual escaped, because of a premonition that made him take another train or make a happy change of cars. Nothing is said of the times when premonitions failed, nor of the disappointments of such dreads. Most people laugh at the stories, but a few individuals become seriously impressed with the possibility of such warnings and then make themselves miserable by having frequent premonitions.

Etiology.—As to the origin of these premonitions it is hard to say. They occur more frequently on dark days than in bright weather and are complained of much more in spring and fall than during the cold brisk winter or during the summer time. A succession of very hot days, however, brings a series of premonitions, especially with regard to accidents by heat, that is not surprising since the newspapers have many accounts of sunstrokes and there is every suggestion of the possibility of danger of this kind. How large a role suggestion plays in the matter can be realized from the fact that after some particularly serious railroad accident many people have premonitions that they may be hurt and occasionally they put themselves to considerable inconvenience in choosing the car in which they will sit, if the last serious preceding accident of which they have heard happens to have brought death mainly in a particular car of a train. It is always suggestible people who are likely to have premonitions. The thought comes very simply at first, they dwell on it a little unwillingly, then they find it impossible to banish it and finally it may become a positive obsession. The soil and the seed for suggestion are both needed to produce premonitions.

Royce suggests that many of the supposedly fulfilled premonitions are really only pseudo-presentiments and represent an instantaneous and irresistible hallucination of memory, which may give rise to the impression that there has been a previous dream or other warning presaging the facts, though no such phenomenon actually took place. In other words, there would be an auto-suggestion consequent upon the hearing of other fulfilled presentiments that sometime some such thing must also occur to us, and then when a happening that reminds us of something in the previous stories of [{636}] presentiments comes there is the sudden responsive feeling "why, this is what I saw or must have seen in my dream."

Podmore suggests an illusion of memory magnifying or rearranging the details of a recent dream or premonitory impression, so as to make it fit into the happenings. Dreams are so vague that unless they have been written down we are not quite sure of them an hour after they occurred and a day or two later we have only the merest hint of what they were. If this can be made to have any connection with a casualty of any kind that happens subsequently we may very readily recreate the dream with its details concordant to the event. Certainly no reliance can be placed on a story of a dream fulfilled unless the dream was told before the happening.