1902 Encyclopedia > Jean-Baptiste Lamarck

Jean-Baptiste Lamarck
(Jean-Baptiste Pierre Antoine de Monet, Chevalier de Lamarck)
French naturalist

JEAN BAPTISTE PIERRE ANTOINE DE MONET, CHEVALIER DE LAMARCK, (1744-1829), a celebrated French naturalist, was born 1st August 1744, at Bazantin, a village of Picardy. He was an eleventh child ; and his father, lord of the manor and of old family, but of limited means, having already placed three sons in the army, destined this one for the church, and sent him to the Jesuits at Amiens, where he continued till his father's death. After this he would remain with the Jesuits no longer, and, not yet seventeen years of age, started for the seat of war at Bergen-op-Zoom, before which place one of his brothers had already been killed. Mounted on an old horse, with a boy from the village as attendant, and furnished by a lady with a letter of introduction to a colonel, he reached his destination on the evening before a battle. Next morning the colonel found that the new and very diminutive volunteer had posted himself in the front rank of a body of grenadiers, and could not be induced to quit the position. In the battle, the company which he had joined became exposed to the fire of the enemy's artillery, and in the confusion of retreat was forgotten. All the officers and subalterns were killed, and not more than fourteen men were left, when the oldest grenadier seeing there were no more French in sight proposed to the young volunteer so soon become commandant to withdraw his men. This he refused to do without orders. These at last arrived ; and for his bravery he was made an officer on the spot, and soon after was named to a lieutenancy.

After the peace, the regiment was sent to Monaco. There it happened that one of his comrades playfully lifted him by the head, and to this it was imputed that he was seized with disease of the glands of the neck, so severe as to necessitate grave surgical interference, and put a stop to his military career.

The courage of Lamarck, so early exhibited, was in future to be shown by the maintenance of his opinions in the absence of any friendly support, and by fortitude amid many adversities ; while his activity was to be displayed, not only in manifold speculation, but in copious and varied scientific work. He went to Paris and began the study of medicine, supporting himself by working in a banker's office. He early became interested in meteorology and in physical and chemical speculations of a chimerical kind, but happily threw his main strength into botany, and in 1778 published his Flore française, a work in which by a dichotomous system of contrasting characters he enabled the student with facility to determine species. This work, which went through several editions and long kept the field, gained for its author immediate popularity as well as the honour of admission to the Academy of Sciences.

In 1781 and 1782, under the title of botanist to the king, an appointment obtained for him by Buffon, whose son accompanied him, he travelled through various countries of Europe, extending his knowledge of natural history ; and on his return he began those elaborate contributions to botany on which his reputation in that science principally rests, namely, the Dictionnaire de Botanique and the Illustrations de Genres, voluminous works contributed to the Encyclopédie Méthodique (1785). In 1793, when he was already forty-nine years of age, in consequence of changes in the organization of the natural history department at the Jardin du Roi, where he had held a botanical appoint-ment since 1788, Lamarck was presented to a zoological chair, and called on to lecture on the Insecta and Vermes of Linnaeus, the animals for which he introduced the term In-vertebrata, still employed. Thus driven, comparatively late in life, to devote his principal attention to zoology instead of botany, he had the misfortune soon after to suffer from impaired vision ; and the malady progressing resulted subsequently in total blindness. Yet his greatest zoological work, the Histoire Naturelle des Animaux sans Vertèbres, was published from 1815 to 1822, with the assistance, in the last two volumes, of his eldest daughter and of M. Latreille. A volume of plates of the fossil shells of the neighbourhood of Paris was collected in 1823 from his memoirs in the Annales des Muséum. The later years of his blind old age were spent in straitened circumstances and accumulating infirmities, solaced, however, by the devotion of his family, and particularly of his eldest daughter, of whom Cuvier records that she never left the house from the time that li? was confined to his room. He died 18th December 1829.

The character of Lamarck as a naturalist is remarkable alike for its excellences and its defects. His excellences were width of scope, fertility of ideas, and a pre-eminent faculty of precise description, arising not only from a singularly terse style, but from a clear insight into both the distinctive features and the resemblances of forms. That part of his zoological work which still finds a large and important place in the science of the present day, and constitutes his solid claim to the highest honour as a-zoologist, is to be found in his extensive and detailed labours in the departments of living and fossil Invertebrata. His endeavours at classification of the great groups were necessarily defective on account of the imperfect knowledga possessed in his time in regard to many of them, e.g., echinoderms, ascidians, and intestinal worms ; yet they are not without interest, particularly on account of the comprehensive attempt to unite in one great division as Articulala all those groups that appeared to present a segmented construction. Moreover, Lamarck was the first to distinguish vertebrate from invertebrate animals by the presence of a vertebral column, and among the Invertebrata to found the groups Crustacea, Arachnida, and Annelida. In 1785 (Hist, de l'Acad.) he evinced his appreciation of the necessity of natural orders in botany by an attempt at the classification of plants, interesting, though crude and falling immeasurably short of the system which grew in the hands of his intimate friend Jussieu. The problem of taxonomy has never been put more philosophically than he subsequently put it in his Animaux sans Vertèbres :— " What arrangement must be given to the general distribution of animals to make it conformable to the order of nature in the production of these beings "

The most prominent defect in Lamarck must be admitte quite apart from all consideration of the famous hypothesis which bears his name, to have been want of control in speculation. Doubtless the speculative tendency furnished a powerful incentive to work, but it outran the legitimate deductions from observation, and led him into the production of volumes of worthless chemistry without experimental basis, as well as into spending much time on fruitless meteorological predictions. His Annuaires Météorologiques were published yearly from 1800 to 1810, and were not discontinued until after an unnecessarily public and brutal tirade from Napoleon, administered on the occasion of being presented with one of his works on natural history.

To the general reader the name of Lamarck is chiefly interesting on account of his theory of the origin of life and of the diversities of animal forms. The idea, which appears to have been favoured by Buffon before him, that species were not through all time unalterable, and that the more complex might have been developed from pre-existent simpler forms, became with Lamarck a belief or, as he imagined a demonstration. Spontaneous generation, he concluded, might be easily conceived as resulting from such agencies as heat and electricity causing in small gelatinous bodies an utricular structure, and inducing a " singular tension," a kind of "erethisme " or " orgasme"; and, having thus accounted for the first appearance of life, he explained the whole organization of animals and forma-tion oi different organs by four laws :—

" 1. Life by its proper forces tends continually to increase the volume of every body possessing it, and to enlarge its parts, up to a limit which it brings about.
" 2. The production of a new organ in an animal body results from the supervention of a new want (besom) continuing to make itself felt, and a new movement which this want gives birth to and encourages.
" 3. The development of organs and their force of action are con-stantly in ratio to the employment of these organs.
"4. All which has been acquired, laid down, or changed in the organization of individuals in the course of their life is conserved by generation and transmitted to the new individuals which pro-ceed from those which have undergone those changes."

It is the second law which has been principally associated with Lamarck's name, and is often referred to as his hypothesis of the evolution of organs in animals by appetence or longing, although Lamarck does not teach that the animal's desires affect its conforma-tion directly, but that altered wants lead to altered habits, which result in the formation of new organs as well as in modification, growth, or dwindling of those previously existing. Thus, he suggests that, ruminants being pursued by carnivora, their legs have grown slender; and, their legs being only fit for support, while their jaws are weak, they have made attack wdth the crown of the head, and the determination of fluids thither has led to the growth of horns. So also the stretching of the giraffe's neck to reach the foliage he supposes to have led to its elongation ; and the kangaroo, sitting upright to support the young in its pouch, he imagines to have had its fore-limbs dwarfed by disuse, and its hind legs and tail exaggerated by using them in leaping. The length to which he carried such notions can be fairly estimated by the illustration which, long after the publication of his Philosophic Zoologique, he selected in the introduction to the Hist. Nat. des Anim. sans Vert. "I conceive that a gasteropod mollusc, which, as it crawds along, finds the need of touching the bodies in front of it, makes efforts to touch those bodies wdth some of the foremost parts of its head, and semis to these every time quantities of nervous fluids, as well as other liquids. I conceive, I say, that it must result from this reiterated afflux towards the points in question that the nerves which abut at these points will, by slow degrees, be extended. Now, as in the same circumstances other fluids of the animal flow-also to the same places, and especially nourishing fluids, it must follow that two or more tentacles wdll appear and develop insensibly in those circumstances on the points referred to."

However absurd this may seem, it must be admitted that, unlimited time having been once granted for organs to be developed in series of generations, the objections to their being formed in the way here imagined are only such as equally apply to the theory of their origin by natural selection. Thus, for example, neither theory considers that it has to deal, not with crude heaps of mere functional organs, but wdth exquisitely orderly forms, nor accounts for the symmetrical first appearance of parts or for sex ; nor, though La-marck tried hard, has he or any later writer reduced to physical law the rise of consciousness in association with structures which in their physical relations are mere mechanisms capable of reflex actions.

In judging the reasonableness of the second law of Lamarck as compared with more modern and now widely received theories, it must be observed that it is only an extension of his third law ; and that third law is a fact. The strengthening of the blacksmith's arm by use is proverbially notorious. It is, therefore, only the sufficiency of the Lamarckian hypothesis to explain the first com-mencement of new organs which is in question, if evolution by the mere operation of forces acting in the inorganic world be granted ; and surely the Darwinian theory is equally helpless to account for the beginnings of a new organ, while it demands as imperatively that every stage in the assumed hereditary development of an organ must have been useful.

Furthermore, to no writer more recent than Lamarck can be attributed the credit of first pointing attention to the repetition of acquired variations in the progeny, or the idea of weaving that fact into a theory of the origin of species. His words are :—"Every-thing which nature has caused individuals to acquire or lose by the influence of the circumstances to which their race is long exposed, and consequently by the influence of the predominant employment of such organ, or Its constant disuse, she preserves by generation to the new individuals proceeding from them, provided that the changes are common to the two sexes, or to those which have produced these new individuals" (Phil. Zool., i. 235). It is interesting to note in this passage that he hesitated to believe that peculiarities could become permanent unless possessed by both parents.

Notwithstanding his attempt to evolve all vital action from the forces at work in the inorganic world, Lamarck made a broad dis-tinction between the "power of life," to which he attributed the production of " a real progression in the composition of the organization of animals," and the modifying effects of external circumstances. The existence of such a progression cannot now be doubted, and constitutes evolution in the only sense in which it is universally admitted. Lamarck, equally with Darwin, teaches the more speculative doctrine that the complex forms are descended from simpler ancestors. In the modus operandi by which they hold this to have been accomplished both have admitted the action of a variety of modifying circumstances. Lamarck gave great importance to the influence of new wants acting indirectly by stimulating growth and use. Darwin has given like importance to the effects of accidental variations acting indirectly by giving advantage in the struggle for existence. The speculative writings of Darwin have, however, been interwoven with a vast number of beautiful experiments and observations bearing on his speculations, though by no means proving his theory of evolution ; wdiile the speculations of Lamarck lie apart from his wonderful descriptive labours, unrelieved by intermixture with other matters capable of attracting the numerous class who, provided they have new facts set before them, are not careful to limit themselves to the conclusions strictly deducible therefrom. But those who read the Philosophie Zoologique wdll find, how many truths often supposed to be far more modern are stated with abundant clearness in its pages. (J. CL.)

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