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.

    the four-element theory (earth, air, water, and fire) was generally accepted in France. He continued to believe in the four elements throughout his life despite the work of Lavoisier and the chemical revolution; for this reason his chemistry has often been dismissed as worthless speculation. Yet Lamarck took it very seriously, and it was an important part of his ideas about nature and evolution.

Lamarck's first work in the field, Recherches sur les causes des principaux faits physiques, was begun in 1776. It was submitted to the Académie des Sciences in 1780 and received an unfavorable report; it was finally published in 1794, after the Academy had been suppressed. Lamarck devoted two other full-length studies to chemistry: Réfutation de la théorie pneumatique (1796) and Mémoires de physique et d'histoire naturelle (1797). He also published two articles in 1799; they were reprinted at the end of his Hydrogéologie (1802), which contained a long chapter relating his chemical theories to his geological theories. Although Lamarck's chemical views were ignored, he continued to hold them; they appear with signs of increasing paranoia in his major evolutionary works. They play the most prominent role in Recherches sur l'organisation des corps vivans (1802), the first full-length exposition of his evolutionary theories.

In Lamarck's four-element theory, differences between compounds depended on both the number and proportion of the elements and the relative strengths of the bonds between the elements in the constituent molecules. Furthermore, each element had a natural state in which it demonstrated its real properties and several modified states in which it was present in compounds. The most important of the four elements in Lamarck's chemistry was fire, which existed in three main states: a natural one and two modified forms, which were fire in a state of expansion (or caloric fire) and fixed fire. Using these three main states and their many internal modifications, Lamarck attempted to account for a great number of chemical and physical phenomena such as sound, electricity, magnetism, color, vaporization, liquefaction, and calcination. Later, in his theory of evolution, he added life as another phenomenon to be explained by activity of fire. For Lamarck, fire not only explained many processes, it also was a constituent principle of compounds. He attempted to show how chemical substances in their various states depended on differing amounts of fixed fire. One temporary form of fixed fire was phlogiston.

Lamarck believed that only living beings could produce chemical compounds. Plants combined free elements directly to produce a number of substances of varying complexity. These in turn were elaborated by the different animals eating the plants, the more complex substances being produced by those animals with the most highly organized physiological structure. The process of compound formation involved modification of the elements away from their natural state and the more complex the substance, the greater the modification. Once the forces of life were removed, by death or the elimination of waste products, the compounds began to disintegrate. The natural tendency of all compounds, therefore, was to decompose until the elements returned to their natural state, in the process producing all known inorganic substances. For the mineral kingdom there was a chain of being with continous degradation from the most complex to the simplest; this chain was composed of individuals rather than species or types of minerals. Lamarck's first statement of his theory of evolution in 1800 showed a similar thought pattern: degradation and irrelevance of species.

In his chemistry, Lamarck showed a speculative orientation and an emphasis on nature as a whole with many interrelated parts and processes. His distinction between the living and the nonliving was crucial to his biology and his view of the mineralogical chain of being was basic to his geology. His chemistry was also later to be very important in his theory of evolution. It was used to provide a materialistic definition of life and to explain its maintenance, appearance (both through reproduction and through spontaneous generation), and the way in which living organisms gradually evolve, including the emergence of the higher mental faculties. Fire, as understood by Lamarck, was the key element in all of these explanations.

Meteorology.

Lamarck's work in meteorology was similar in many respects to that in chemistry. Although one of his earliest scientific interests, he did not publish anything until the late 1790's; he experienced the same general lack of reception of his work in chemistry. Meteorology was the first scientific area in which Lamarck prepared a memoir and one which was well received by the Academy. The manuscript of this unpublished memoir (Muséum National d'Histoire Naturelle, Paris, MS 755-1) shows that as early as 1776, Lamarck was interested in the effects of climate on living organisms. It is highly probable that Lamarck's interest in chemistry resulted from his concern with certain aspects of meteorology. His general approach to science is also evident in this early manuscript: his emphasis is on the general principles, and he manifests disdain toward those devoted solely to the collection of little facts. The extent to which Lamarck saw his meteorology as part of his whole view of nature is indicated later in his