Lamarck, the Founder of Evolution: His Life and Work

by A. S. Packard

“Why,” he asks, “should not heat and electricity act on certain matters under favorable conditions and circumstances?” He quotes Lavoisier as saying (Chémie, i., p. 202) “that God in creating light had spread over the world the principle of organization of feeling and of thought”; and Lamarck suggests that heat, “this mother of generation, this material soul of organized bodies,” may be the chief one of the means which nature directly employs to produce in the appropriate kind of matter an act of arrangement of parts, of a primitive germ of organization, and consequently of vitalization analogous to sexual fecundation.

“Not only the direct formation of the simplest living beings could have taken place, as I shall attempt to demonstrate, but the following considerations prove that it is necessary that such germ-formations should be effected and be repeated under favorable conditions, without which the state of things which we observe could neither exist nor subsist.”

His argument is that in the lower polyps (the Protozoa) there is no sexual reproduction, no eggs. But they perish (as he strangely thought, without apparently attempting to verify his belief) in the winter. How, he asks, can they reappear? Is it not more likely that these simple organisms are themselves regenerated? After much verbiage and repetition, he concludes:

“We may conceive that the simplest organisms can arise from a minute mass of substances which possess the following conditions—namely, which will have solid parts in a state nearest the fluid conditions, consequently having the greatest suppleness and only sufficient consistence to be susceptible of constituting the parts contained in it. Such is the condition of the most gelatinous organized bodies.

“Through such a mass of substances the subtile and expansive fluids spread, and, always in motion in the milieu environing it, unceasingly penetrate it and likewise dissipate it, arranging while traversing this mass the internal disposition of its parts, and rendering it suitable to continually absorb and to exhale the other environing fluids which are able to penetrate into its interior, and which are susceptible of being contained.

“These other fluids, which are water charged with dissolved (dissous) gas, or with other tenuous substances, the atmospheric air, which contains water, etc., I call containable fluids, to distinguish them from subtile fluids, such as caloric, electricity, etc., which no known bodies are believed to contain.

“The containable fluids absorbed by the small gelatinous mass in question remain almost motionless in its different parts, because the non-containable subtile fluids which always penetrate there do not permit it.

“In this way the uncontainable fluids at first mark out the first traces of the simplest organization, and consequently the containable fluids by their movements and their other influences develop it, and with time and all the favorable circumstances complete it.”

This is certainly a sufficiently vague and unsatisfactory theory of spontaneous generation. This sort of guess-work and hypothetical reasoning is not entirely confined to Lamarck’s time. Have we not, even a century later, examples among some of our biologists, and very eminent ones, of whole volumes of à priori theorizing and reasoning, with scarcely a single new fact to serve as a foundation? And yet this is an age of laboratories, of experimentations and of trained observers. The best of us indulge in far-fetched hypotheses, such as pangenesis, panmixia, the existence of determinants, and if this be so should we not excuse Lamarck, who gave so many years to close observation in systematic botany and zoölogy, for his flights into the empyrean of subtle fluids, containable and uncontainable, and for his invocation of an aura vitalis, at a time when the world of demonstrated facts in modern biology was undiscovered and its existence unsuspected?

The Preëxistence of Germs and the Encasement Theory.—Lamarck did not believe in Bonnet’s idea of the “preëxistence of germs.” He asks whether there is any foundation for the notion that germs “successively develop in generations, i.e. in the multiplication of individuals for the preservation of species,” and says:

“I am not inclined to believe it if this preëxistence is taken in a general sense; but in limiting it to individuals in which the unfertilized embryos or germs are formed before generation. I then believe that it has some foundation.—They say with good reason,” he adds, “that every living being originates from an egg.... But the eggs being the envelope of every kind of germ, they preëxist in the individuals which produce them, before fertilization has vivified them. The seeds of plants (which are vegetable eggs) actually exist in the ovaries of flowers before the fertilization of these ovaries.”[112]

From whom did he get this idea that seeds or eggs are envelopes of all sorts of germs? It is not the “evolution” of a single germ, as, for example, an excessively minute but complete chick in the hen’s egg, in the sense held by Bonnet. Who it was he does not mention. He evidently, however, had the Swiss biologist in mind, who held that all living things proceed from preëxisting germs.[113]

Whatever may have been his views as to the germs in the egg before fertilization, we take it that he believed in the epigenetic development of the plant or animal after the seed or egg was once fertilized.[114]

Lamarck did not adopt the encasement theory of Swammerdam and of Heller. We find nothing in Lamarck’s writings opposed to epigenesis. The following passage, which bears on this subject, is translated from his Mémoires de Physique (p. 250), where he contrasts the growth of organic bodies with that of minerals.