we take infancy and old age fairly into the calculation. The sleep and various states of semi-consciousness produced by mesmeric or other unwonted means, we look upon with awe and amazement; forgetting, in their familiarity, those equally strange phenomena under which we periodically pass this portion of our existence. The dull book lulling its reader into slumber, or the cushioned arm-chair and warm fireside inviting sleep, may well be termed mesmeric agents, as regards this change of state; though wanting those accessories of nervous temperament, and that strange mixture of credulity and fraud, so often noted in persons who are the subjects of mesmeric experiment. We have hitherto been speaking of life in its larger and physiological sense. We now come to that more especial view of it indicated by the title of the volume before us: in pursuing this subject, however, it will be still needful to recur occasionally to the more general theory for aid and illustration. The questions regarding human longevity are far too complex to be submitted to any single solution, or separated from the elementary consideration of life itself. The name and repute of M. Flourens in the scientific world might well warrant some high expectations of a work coming from him, and bearing this title. His position in the Institute of France, and in other great European Societies, and his prior remarkable researches in experimental physiology, afforded a reasonable pledge that whatever he wrote on this interesting topic would be marked by a large and close observation of facts, and by sound deductions from them. We are bound to say that this expectation is in no way fulfilled by the treatise before us; the greatest merit of which is that it is not long, and not otherwise tedious than through its loose and inconsecutive reasoning. The result he seeks to establish as to human longevity we consider to be unfounded; and the arguments offered on behalf of it vague and unsatisfactory. Of this part of his work we shall speak more in detail hereafter, as this question will form the main subject of the present article. Meanwhile we shall content ourselves with a very cursory notice of the latter half of the volume, indicated in the title-page by the phrase, De la Quantité de Vie sur le Globe.' Though aware that this phrase is borrowed from Buffon, we still claim the right to object to it here; as an affectation of higher philosophy and greater originality than really belongs to this portion of M. Flourens's work. What he gives us is, in truth, little more than a partial and disjointed discussion of those modern discoveries in Paleontology, and the relations of animal life to the successive and various conditions of the globe, which form an æra in the history of science; but which he evidently only imperfectly comprehends. The doctrine of Buffon, upon which his own views are founded, is this; that taking all created beings into account, the total quantity of life on our earth is always the same that the Creator has brought into being an incalculable number of living organic molecules, indestructible and common to all organised beings, the material of generation, growth, and duration of existence that death, while it destroys and dissolves individual forms or lives, does not annihilate these molecules, which pass into other forms, giving and maintaining life as before, and being always the same in total quantity on the globe. This is one of the many fruitless hypotheses, common to every age; easy to construct, difficult absolutely to refute or deny, impossible to prove. The molécules organiques vivantes of Buffon, like the plastic nature of Cudworth, are an effort to shelter penury of knowledge under the garb of scientific language. Though the higher genius of Leibnitz gave somewhat more of philosophy to his monads, yet essentially the attempt and the failure are the same. Life may be defined, more or less justly, in its functions. In its elements, no reason or hypothesis can reach it. M. Flourens, however, while professing admiration of Buffon's genius, and acquiescence in the hypothesis as to the equal and constant quantity of life on the globe, places this doctrine on a basis of his own, which we may briefly give in his own words: 'Je n'étudie la vie, ni dans les molécules organiques, ni dans les monades. J'étudie la vie dans les êtres vivants; et je trouve deux choses: la première que le nombre des espèces va toujours en diminuant, depuis qu'il y a des animaux sur le globe; et la seconde que le nombre des individus, dans certaines espèces, va toujours au contraire en croissant; de sorte que, à tout prendre, et tout bien compté, le total de la quantité de vie, j'entends le total de la quantité des êtres vivants, reste toujours en effet à peu près le même.' No evidence for this doctrine is known to us, and assuredly none is furnished by our author to justify its enunciation as a special discovery. It is very true, as M. Flourens states, that various species of animals some of them, as attested by their bones, of gigantic size-have become extinct during what may be called the existing epoch in the history of the globe-that others are probably in progress towards extinction-and that no new creation is known, within this period, of animals of equivalent size, to replace those thus vanishing from the earth. It is also true that many of the domesticated species, serving to the uses of man, have been largely increased in numbers, an effect VOL. CV. NO. CCXIII. E of the increase of human population on the globe. But these things, which are true, are not new; and the doctrine derived from them, that a balance is struck between the two opposed conditions, and that the total quantity of life, or of living beings, remains always nearly the same,--is one wholly unsupported by the premisses. Its wording, indeed, betrays the author's hesitation as to its truth. The à peu près' is a great discounter of realities in science, as in most other things. It will be obvious, indeed, to all who care to reason on the subject, that we have no knowledge, or means of obtaining it otherwise than by vague approximation, as to the total quantity of life on the globe, or the relative quantity at different periods. Such phraseology then, except as denoting mere hypothetical questions, cannot rightly be admitted into scientific language; seeing especially how little we are able to estimate numbers or individualities of life in any of the great classes of the animal kingdom-how impossible to conjecture them in the multitude of those lower forms which we reach only through the eye of the microscope. Nor in fact can any such conclusions as those put forward by M. Flourens be accepted, as long as doubts exist as to the proper definition of species, and the possibility of their change or transmutation in long periods of time. We may not acquiesce in these doubts;—but they are entertained by many, and tend to complicate every part of the inquiry. Dismissing, however, this subject, which it is not necessary to pursue further, we come to the main topic of M. Flourens's volume, the longevity of Man. We wish to deal fairly with his doctrine, and shall state it as clearly as we can. But here, again, we have to complain of the loose and desultory character of his reasoning, broken by numerous citations from other writers, poets as well as physiologists, and many of them little fitted to serve as authorities in a scientific treatise. We have been accustomed to look into the pages of Molière, Voltaire, and La Fontaine for satire upon human life, and not for sober reasoning upon longevity. 6 M. Flourens propounds his main question in these terms: Quelle est la durée naturelle, ordinaire, normale de la vie de l'homme?' And he instantly replies to this question by a passage from Buffon, which he takes as the text and authority for his own views. L'homme qui ne meurt pas de maladies accidentelles, 'vit partout quatre-vingt-dix, ou cent ans.' Though we might comment on the tautology of naturelle and normale as applied to the term of life, we can find no other fault in this manner of propounding the theme. In adopting the conclusion of Buffon, he follows the same train of reasoning to it. He affirms that the duration of life depends neither on climate, nor food, nor race, nor any external condition, but has relation solely to the natural constitution and intrinsic vigour (vertue intrinsèque) of our organs. Regarding everything in the animal economy as submitted to fixed laws that every animal species has its determinate shape and size, its particular time of gestation and period of growth-he infers that the natural duration of life must be equally definite for each species, and open to determination. Still following Buffon at each step, M. Flourens accepts his doctrine that this measure of life is to be found in a certain proportion to that of complete growth, as well in man as in other animals. He differs only as to what may be taken as the term or limit of this growth. Buffon, naturally enough, makes stature his index; and assuming the average period of growth in height in man to be about sixteen years, he takes six or seven periods, the multiples of this time, to express the natural duration of human life. He fortifies himself in this result, by observation of a proportion of time of growth to the length of life in other animals, the horse, dog, stag, &c.; but neither numerically nor otherwise does he claim for his doctrine the absolute exactness of a physical law. The whole duration of life may in some 'measure be calculated by that of the period of growth. Man, 'who is fifteen years in growth, may live six or seven times that 'period, &c.' M. Flourens is bolder in his conclusions, and in the same degree further removed from truth. He adopts as the term or limit of bodily growth (accroissement), the complete union of bones at their Epiphyses an expression we shall speedily explain-and alleging this consummation of growth to occur in man at the age of twenty, and in certain other animals at other ages, in each respectively the fifth part of the term of life, he at once multiplies by 5 the 20 years of human growth, and pronounces 100 years as the natural period of human existence. We produce this view in his own words: 'Buffon says that every animal lives about six or seven times as long as it is in growing. On this supposition the relation would be as 1 to 6 or 7; but the real relation of the period of growth to the duration of life is as 1 to 5, or nearly so. Man is 20 years growing, and he lives five times 20 years, or to 100. The camel is 8 years growing, and he lives to 40: the horse 5 years growing, and he lives to 25; and so on to other animals. We have thus then, at last, an accurate criterion which gives us with certainty the period of growth. The duration of that period gives us the duration of life.' The argument, thus put, is more summary in manner than satisfactory in substance. We doubt much whether this period of epiphysis, or completion of bony union, has been determined in a sufficient number of animals, and with sufficient exactness, to serve as a basis for numerical results. We believe further, that the relation of this period to the normal duration of life in different animals, is nothing more than that general proportion which every successive period bears to its antecedents and consequents; rendering each, in some sort, a measure and index to the rest. What is called epiphysis is a very limited phenomenon of growth; and though seemingly the last in the series of osseous developments, cannot be admitted as an epoch in life, or as having any important relation to other structural changes. We dispute then, altogether, the right of M. Flourens to take it as an axiom, and by applying his multiple of five, to make it tally with what is evidently a foregone conclusion of his own as to the length of life. This conclusion is not logically attained, and is manifestly in contradiction to all experience.* He appeals, however, to experience on behalf of his doctrine that one hundred years is the natural life of man; and that its curtailment below this normal term is the result of those errors and excesses in the manner of living which impair the organs and produce premature decay. And his argument here mainly lies in the citation of some of those cases in which life has been prolonged far beyond the average limit-instances often of exaggerated or doubtful kind, but yet numerous and authentic enough to be admitted as positive facts in the natural history of man. While justly sceptical as to the instances that go beyond our own experience, we cannot rightly dispute the statements coming to us from various sources, from different countries and periods of time, that human beings have occasionally reached, and now and then exceeded, the extraordinary age of 150 years. In our own country, for example, though we may put aside as unproved the case of Henry Jenkins, alleged (chiefly, though not solely, on his memory of the battle of Flodden Field) to have As well might we reason from the old Highland proverb which says, 'Thrice the life of a dog is the life of a horse; Thrice the life of a stag is the life of a crow.' The traditional longevity of the stag and the crow are still, we believe, unsolved problems, but there is nothing in the period of their respective growths to bring them within M. Flourens's theory. |