LAMARCK, JEAN BAPTISTE PIERRE ANTOINE DE MONET DE (b. Bazentin-le-Petit, Picardy, France, 1 August 1744; d. Paris, France, 28 December 1829), botany, invertebrate zoology and paleontology, evolution.

    scientific community resulted from the publication of his Flore françoise in 1779 (not 1778 as the title page says). His innovation was the establishment of dichotomous keys to aid in the identification of French plants; by eliminating large groups of plants at each stage through the use of mutually exclusive characteristics, the given name of any plant could be rapidly determined. This “method of analysis,” as Lamarck called it, was much easier to use in identifying plants than Linnaeus' artificial system of classification, which was based on sexual differences among plants or the natural methods of classification then developing in France with the work of Adanson, Bernard de Jussieu, and Antoine Laurent de Jussieu. Lamarck's new approach and his criticisms of Linnaeus impressed Buffon, who arranged to have the Flore published by the government. The first of the three volumes contained a theoretical “Discours préliminaire” which, among other things, explained the method of analysis and a lengthy exposition of the fundamentals of botany. The other two volumes listed all known French plants according to his method of classification and provided good descriptions of each species. The Flore was one of the first French works to include the Linnaean nomenclature as well as that of Tournefort. Written in French rather than Latin, the Flore was an immediate success and the first printing was sold out within the year; in 1780 the work was reprinted. Lamarck had various plans for a new edition but was unable to carry them out for lack of funds. Finally, in 1795, the Flore was reprinted; although it did not differ from the first edition, it was called a second edition. In 1802 Lamarck, who was too busy doing other things, turned the preparation of a new edition over to A. P. de Candolle, who published what is called the third edition in 1805. Candolle made major revisions, replacing Lamarck's system of classification with that of A. L. de Jussieu and revising the section on the fundamentals of botany to include new scientific discoveries. Ten years later this third edition was reprinted and another volume was added to include species previously unknown or overlooked.

Lamarck's other major work in botany was his contribution to the Dictionnaire de botanique, which formed part of the larger Encyclopédie méthodique. He wrote the first three and a half of eight volumes; they were published in 1783, 1786, 1789, and 1795. Lamarck composed a long “Discours préliminaire,” articles on all aspects of botany including classification and the structures of plants, and articles describing specific plants and their classificatory groupings. The companion piece to the Dictionnaire, the Illustration des genres, appeared in three volumes in 1791, 1798, and 1800. It included about 900 plates, descriptions of genera arranged according to Linnaeus' system of classification, and a listing of all known species in these genera. Lamarck himself had identified several new genera and species; he published these discoveries as articles in various publications from 1784 to 1792.

In addition to devising a new and useful method for the identification of plants and doing systematic botany, Lamarck demonstrated a number of theoretical and philosophical interests in his botanical works. In the “Discours préliminaire” of the Flore, Lamarck made his first attempt to formulate a natural method of classification for the vegetable kingdom. His aim was to discover the position every vegetable species should occupy in a graduated unilinear chain of being on the basis of comparative structural relationships. Unable to achieve this, he had to settle for a natural order at the level of the genera and even this was very tentative. Although he shared a common assumption of the time, that a natural classification would begin with the most complex and descend to the simplest organism, he found that in practice it was easier to work in the opposite order. This order would later be an essential feature of his evolutionary theory. Lamarck intended to develop his natural method in a work which was to be entitled Théâtre universel de botanique. The proposed work was to include all members of the vegetable kingdom, not just those found in France; it was never written.

In the “Discours préliminaire” of the Flore, Lamarck showed the orientation of a naturalist philosopher concerned more with the broad problems than the little facts, as he called them. He conceived of nature as a whole composed of living and nonliving things, the former divided into plants and animals. It was the view of the whole, its processes, and interrelations which really interested him.

Lamarck, in the same work, demonstrated his awareness of the important influence of the environment, especially climate, on vegetable development. He noted that two seeds from the same plant growing in two very different environments would become two apparently different species. Lamarck was particularly conscious of the changes plants undergo in artificial cultivation and he referred to such changes as degradations, the term he first used in describing evolutionary processes in 1800. In 1779, however, Lamarck still believed in fixed species and thought of the environment as the factor responsible for the production of varieties; by 1800 he had extended these views on the production of varieties to the origin of all organisms below the level of classes.

In 1779 Lamarck also demonstrated his genetic approach to a subject; the present is understood by tracing the historical steps that produced it, beginning