Natural Science 14: 290-295 (April, 1899)

The True Interpretation of Lamarck's Theories: A Plea for their Reconsideration.

THAT Lamarck has been misinterpreted and misunderstood from his day to this, appears to me to be due to two causes chiefly, first, the lack of true biological and physiological knowledge in his day, which led not only to the rejection of his theories by his contemporaries, but also gave origin to the second cause of misinterpretation, viz. the obscurity and ambiguity of his language.

Having succeeded, as I believe, in developing his true meaning, I now desire to bring my views to the notice of evolutionists, believing that this interpretation will make clear many obscure organic phenomena, as well as enable us to do full justice to that great philosopher.

In summing up the opinions of biologists on Lamarck Mr. G. Sandeman thus writes ("Problems of Biology," p. 153): "It is certain that this biologist has been, on the whole, misinterpreted, but, on the other hand, it is not easy to be sure that one understands him. And the confusion has taken place chiefly over that key-word of his system—besoin, or need." Again he states: "It—besoin—probably appeared to Lamarck to have a quite definite meaning requiring no further analysis."

Mr. Sandeman is quite right in the above statement, for, as I shall show, the whole misinterpretation of Lamarck is due to the nonperception by biologists of the true meaning of this need or desire. Moreover, it will be pointed out that Lamarck himself failed to see the true interpretation in some respects, and hence the full significance of his important conclusions and laws.

Mr. Clodd has well said ("Story of Creation," p. 93): "The functions of living things are threefold—nutrition, reproduction, and relation, in other words to feed, to multiply, to respond to the outer world." There is, however, one special relation which, although included in the last of those, yet requires more attention than Mr. Clodd has bestowed on it, viz. the relations which living things have with other living things, especially as regards protection.

At this stage, it is well to consider carefully the nature of functions, because we cannot understand Lamarck unless we keep in view the functional life of living things, and endeavour to understand clearly the true nature of a function. A function is the use which an organ serves. All living things possess organs, the uses of which are called functions. Moreover, there are functions which require, not only their proper organs, but also other auxiliary organs for their effective performance. But functions, and hence organs, vary in importance. There are certain functions so highly important to life and the propagation of the species, that special centres in the central nervous system are found to preside over and control them, giving origin to the need or desire for satisfying them. Such functions are nutrition, reproduction, and, to some extent, protection, and it is in response to the need or desire of the organism that such functions are satisfied.

It is doubtful if any one will be found to dispute the importance of those functions, or their connection with the need or desire emanating from the brain for their satisfaction.

Now it is held as a truism by biologists that "the function makes the organ." That this is so must withstand any attempt at refutation, for it is inconceivable that the organ was first to appear, to be subsequently followed by the function. Stress is laid on this point, because the whole interpretation of Lamarck hangs on its recognition. Further, we can well understand that the nature of the function, i.e. the manner in which the need or desire presiding over the function is satisfied, determines the structural nature of the organ. Change the method of satisfying the function and we may change the structural nature of the organ. But we must also remember that the most important functions have not only their proper organs, but also other auxiliary organs which are brought into new uses when the methods of satisfying the functions are changed. If, e.g., an animal subsisting on surface vegetation, etc., be driven to climb trees in order to satisfy its desire for food, as it is said the mongoose in Jamaica now sometimes does, while the true organs of nutrition will doubtless undergo little if any change, yet, if the habit through any cause, such as continuous drought, etc., be fully established, the auxiliary organs—the feet and claws-will gradually be modified until they serve fully the function of nutrition, i.e. until the feet and claws fully serve the purpose of procuring food. We should then get undoubtedly, in the case of the mongoose, a change towards a squirrel-like type. We thus learn how correlated are different and distant organs in maintaining the integrity of the most important functions.

Bearing the above facts in mind, we are now prepared to consider the theories of Lamarck. These theories he condensed into certain formulae and laws, which are as follows:

(1) "That every change which is at all considerable and continuously maintained in the circumstances of each race of animals, effects in it a real change in their needs."

(2) "That every change in the needs of animals necessitates other actions on their part for the satisfaction of the new needs, and, in consequence, other habits."

(3) "That since every new need requires new actions to satisfy it, it demands of the animal which experiences it either the more frequent use of such a part as was formerly less used, so that it becomes considerably developed and enlarged; or the use of new parts which insensibly arise in the organism from the needs, by the efforts of its inner feelings, as I shall presently show from known facts. And to arrive at the true cause of so many different forms, and so many various habits, as are seen in the animal world, one must recognise that the infinitely diversified but slowly changing circumstances in which the animals in each race have successively been placed, have brought about in each race new needs and consequently changes in their habits. As soon as one has recognised this incontestable truth it will be easy to perceive how the new needs can have been satisfied, and the new habits taken on, if one attends to these two laws of nature, which have always been corroborated by observation."

"First Law.—In every animal which has not passed the limits of its development, the more frequent and sustained use of any organ gradually strengthens that organ, develops it, increases its size, and gives it a strength proportional to the use in question; while the constant disuse of such an organ insensibly weakens and deteriorates it, progressively diminishes its faculties, and finally results in its disappearance."

"Second Law.—All that nature has caused to be acquired by, or lost to, individuals through the influence of the circumstances to which their race has long been exposed, and therefore through the predominant use of an organ, or through the constant disuse of a part, she preserves by reproduction for the new individuals which come from them; provided that the acquired changes are common to the two sexes, or to those which have produced the individuals."

Before entering on the further explanation of Lamarck's key-word, need or desire, I have to point out an almost fatal error in Lamarck's language when stating the above conclusions. Lamarck therein speaks of new needs, but careful consideration of his conclusions has enabled me to see that he really did not mean new needs, but that he referred under such a term to new methods of satisfying the customary needs of animals, as e.g. the need of food, etc. Instead, then, of speaking of new needs he should have said new uses of parts in order to satisfy the functional needs of the animal. This error has been, I believe, a stumbling-block to many in interpreting Lamarck. I myself did not see the error until long after I understood the true meaning of his need or desire. Corrected in the light of this discovery his conclusions read thus:—

(1) That every change which is at all considerable, and continuously maintained in the circumstances of each race of animals, may effect in it a real change in the methods of satisfying their needs, and hence new uses of parts hitherto used in a different way.

(2) That every such change in the methods of satisfying their needs necessitates other actions on their part, and in consequence new habits involving new uses of parts.

(3) That since every new method of satisfying their needs requires new actions, it demands of the animal which experiences it either the more frequent use of such a part as was formerly less used, so that it becomes considerably developed and enlarged, or the use of new parts, which gradually arise in response to the desire or need. And so to arrive at the true cause of so many different forms, and so many various habits, as are given in the animal world, one must recognise that the infinitely diversified and slowly changing circumstances in which the animals of each race have successively been placed have brought about, in each race, new methods of satisfying their functions, and consequently new habits, including the new uses of all correlated parts affected thereby, etc.

As regards the two laws of Lamarck, they are correctly stated, and their truth can be perceived by paying attention to the above corrections.

A careful study of the above conclusions as corrected, and comparison with Lamarck's own statement, must put their signification in a somewhat different light from that suggested by his language.

From what has been already stated, it must be understood that what Lamarck meant by need or desire was not, as is usually understood, an indefinite need or desire, but those needs or desires of animals which lead to the satisfying of their most important functions to ensure their existence and propagation. I myself did not at first understand Lamarck, but on reading of the reversion of the tame pig to the wild boar in the New World, the true meaning suddenly flashed on me in this way: One of the most significant changes in the wild boar from the tame pig is as regards the ear, which in the former is small and erect, and in the latter large and pendent. On reading this statement, my mind instantly saw the analogy between the ear so modified in freedom, and the semi-erect ears of half-tame pigs in the West Indies. I had frequently seen on such pigs the effect of a noise: they would at once erect their ears and scamper off; and I soon saw that the tame pig, escaping from the Spanish settlements in America, would, in order to avoid danger, have more and more frequently to erect their ears to catch the earliest signs of danger, and that this frequent erection, in order to protect themselves, would gradually cause the ears to lose the superfluous fat and develop muscle, with a corresponding decrease in size, until the ear became like that of the wild boar, and thus efficient for the purpose it served in the catching of the earliest sign or sound of danger; and as the modification of character was an innate one that is, in response to the need or desire of the animal—the ear, through heredity, would gradually revert to that of the wild boar. And in a similar way the tame pig would gradually lose all its character due to domesticity, and assume those compatible with a wild life. And we see the same gradual modification of ear in dogs that hunt by scent (e.g. the blood-hound), the ears, relatively little used, gradually enlarge, and become more and more pendent.

It may be thought that the foregoing has reference only to "use and disuse," and the modification of characters induced thereby; but to take such a limited view of the changes brought about, in accordance with Lamarck's laws, would be wrong. The laws of Lamarck have reference to changes of a far wider and deeper nature than is understood by the use of the phrase "use and disuse." The modifications of characters produced by changes in the circumstances of animals bear, not only on the use and disuse of special parts, but also on all other auxiliary organs which co-operate in satisfying the wants or needs of animals, which changes in their circumstances have affected. When we consider the many different parts or characters which are brought into co-operative action when an animal, through a change of circumstances, is forced, through its desire for food, to adopt a new method of feeding—when we consider, also, the changes in the nutritive organs, which a radical change in the nature of the food may entail—we begin to realise the many changes, external and internal, which changes in the circumstances of animals may bring about.

Lamarck's theory, as here developed, explains how, granted that a change of habits in any species may produce changes in special as well as correlated organs, and may affect, not individuals only, but a species as a whole, new species appear in a comparatively short time, owing to the fact that all such modifications of characters are fixed through heredity, thus accounting for the absence of transition forms in many instances—a fact which research proves.

It may be well to state how, by the Lamarckian theory, the two kinds of characters, innate and acquired, are explained. Innate characters, on this theory, are those derived through the wants or needs of the animal, i.e. through the central nervous system. As they are brought about en masse they affect both sexes alike; hence, through heredity, they become fixed, and the species is modified thereby. Acquired characters, on the other hand, are derived through the surrounding conditions, such as climate, etc. Their relation with the nervous system is only through reflex nerves. When the whole of the reflex nerves are affected, as in the case of a tropical sun on the skin, in process of time the central nervous system becomes modified, and the acquired character becomes fixed or innate. On the contrary, characters such as mutilations and scars, which only affect a few of the reflex nerves, do not become innate, or capable of being transmitted, because the unaffected reflex nerves, being in the vast majority, maintain the integrity of the reflex nerve centre—of even that portion pertaining to the affected nerves.

The gradual change taking place in the ear of the tame pig, in response to its desire to escape its enemies in its reversion to the wild boar, is a good example of an innate character; the gradual tanning of the skin, or darkening of the complexion of the Boers of South Africa, a good example of the conversion of an acquired character, affecting the whole of the same reflex nerves, into an innate one; the non-transmission of scars, etc., a good illustration of an acquired character, which, only affecting a few reflex nerves, does not become in time innate, and so capable of being transmitted, except, perhaps, in very rare cases. Innate characters are voluntarily derived; acquired characters, involuntarily.