“The body of this living being not having been formed by juxtaposition, as most mineral substances, that is to say, by the external and successive apposition of particles aggregated en masse by attraction, but essentially formed by generation, in its principle, it has then grown by intussusception—namely, by the introduction, the transportation, and the internal apposition of molecules borne along and deposited between its parts; whence have resulted the successive developments of parts which compose the body of this living individual, and from which afterwards also result the repairs which preserve it during a limited time.”
Here, as elsewhere in his various works, Lamarck brings out the fact, for the first time stated, that all material things are either non-living or mineral, inorganic; or living, organic. A favorite phrase with him is living bodies, or, as we should say, organisms. He also is the first one to show that minerals increase by juxtaposition, while organisms grow by intussusception.
No one would look in his writings for an idea or suggestion of the principle of differentiation of parts or organs as we now understand it, or for the idea of the physiological division of labor; these were reserved for the later periods of embryology and morphology.
Origin of the First Vital Function.—We will now return to the germ. After it had begun spontaneous existence, Lamarck proceeds to say:
“Before the containable fluids absorbed by the small, jelly-like mass in question have been expelled by the new portions of the same fluids which reach there, they can then deposit certain of the contained fluids they carry along, and the movements of the contained fluids may apply these substances to the containing parts of the newly organized microscopic being. In this way originates the first of the vital functions which becomes established in the simplest organism, i.e., nutrition. The environing containable fluids are, then, for the living body of very great simplicity, a veritable chyle entirely prepared by nature.
“Mutilation cannot operate without gradually increasing the consistence of the parts contained within the minute new organism and without extending its dimensions. Hence soon arose the second of the vital functions, growth or internal development.”
First Faculty of Animal Nature.—Then gradually as the continuity of this state of things within the same minute living mass in question increases the consistence of its parts enclosed within and extends its dimensions, a vital orgasm, at first very feeble, but becoming progressively more intense, is formed in these enclosed parts and renders them susceptible of reaction against the slight impression of the fluids in motion which they contain, and at the same time renders them capable of contraction and of distention. Hence the origin of animal irritability and the basis of feeling, which is developed wherever a nervous fluid, susceptible of locating the effects in one of several special centres, can be formed.
“Scarcely will the living corpuscle, newly animalized, have received any increase in consistence and in dimensions of the parts contained, when, as the result of the organic movement which it enjoys, it will be subjected to successive changes and losses of its substance.
“It will then be obliged to take nourishment not only to obtain any development whatever, but also to preserve its individual existence, because it is necessary that it repair its losses under penalty of its destruction.
“But as the individual in question has not yet any special organ for nutrition, it therefore absorbs by the pores of its internal surface the substance adapted for its nourishment. Thus the first mode of taking food in a living body so simple can be no other than by absorption or a sort of suction, which is accomplished by the pores of its outer surface.
“This is not all; up to the present time the animalized corpuscle we are considering is still only a primitive animalcule because it as yet has no special organ. Let us see then how nature will come to furnish it with any primitive special organ, and what will be the organ that nature will form before any others, and which in the simplest animal is the only one constantly found; this is the alimentary canal, the principal organ of digestion common to all except colpodes, vibrios, proteus (amœba), volvoces, monads, etc.
“This digestive canal is,” he says—proceeding with his à priori morphology—“a little different from that of this day, produced by contractions of the body, which are stronger in one part of the body than in another, until a little crease is produced on the surface of the body. This furrow or crease will receive the food. Insensibly this little furrow by the habit of being filled, and by the so frequent use of its pores, will gradually increase in depth; it will soon assume the form of a pouch or of a tubular cavity with porous walls, a blind sac, or with but a single opening. Behold the primitive alimentary canal created by nature, the simplest organ of digestion.”
In like à priori manner he describes the creation of the faculty of reproduction. The next organ, he says, is that of reproduction due to the regenerative faculty. He describes fission and budding. Finally (p. 122) he says:
“Indeed, we perceive that if the first germs of living bodies are all formed in one day in such great abundance and facility under favorable circumstances, they ought to be, nevertheless, by reason of the antiquity of the causes which make them exist, the most ancient organisms in nature.”
In 1794 he rejected the view once held of a continuous chain of being, the échelle des êtres suggested by Locke and by Leibnitz, and more fully elaborated by Bonnet, from the inorganic to the organic worlds, from minerals to plants, from plants to polyps (our Infusoria), polyps to worms, and so on to the higher animals. He, on the contrary, affirms that nature makes leaps, that there is a wide gap between minerals and living bodies, that everything is not gradated and shaded into each other. One reason for this was possibly his strange view, expressed in 1794, that all brute bodies and inorganic matters, even granite, were not formed at the same epoch but at different times, and were derived from organisms.[115]