The original text of the 1st edition (1859) says:
From the facts alluded to in the first chapter, I think there can be little doubt that use in our domestic animals strengthens and enlarges certain parts, and disuse diminishes them; and that such modifications are inherited. Under free nature, we can have no standard of comparison, by which to judge of the effects of long-continued use or disuse, for we know not the parent-forms; but many animals have structures which can be explained by the effects of disuse.
The excerpt, as you can easily see by the publication date, is from Charles Darwin, not from Jean Baptiste de Monet (aka Chevalier de Lamarck).
During our entire academic life, on both sides of the process (first as students and then as teachers) we talk — and we hear about — the inherent antithesis, the undeniable antagonism between the transmission of hereditary characteristics according to Lamarck (the inheritance of acquired characteristics) and the transmission of hereditary characteristics according to Darwin (not using such inheritance). At least, this is what happens in the country where I studied. This antagonism has been extensively explored in countless high school exams and in almost every university entrance assessment, and it is listed in the main textbooks. Few notions on biology are so heavily repeated, and almost always in the same way. However, to what extent does this antagonism exist? And to what extent, if any, does its analysis has been correctly formulated?
I think we can easily show the fragility of this concept, produced largely throughout the 20th century. First, the reading of “On the origin of species” makes it clear (mainly in chapters I, II and V) that the inheritance of acquired characteristics was seen seriously by Darwin (Ernst Mayr, in his introduction to the facsimile of the 1st Edition — Harvard University Press — list all pages where Darwin talks about the importance of the use and disuse of body parts in the transmission of acquired characteristics to offspring: 11, 43, 134, 135, 136, 447, 454, 455, 472, 473, 479 and 480). Darwin was, and about that little doubt remains, a genius, and his contribution to mankind’s knowledge was one of the most important in the last 500 years, no exaggeration here. However, he was, as every scientist is, a person inserted in the paradigms of his time, and the inheritance of acquired characteristics (by no means a concept created by Lamarck) will only lose its force in the late 19th century (see August Weismann), already close to Darwin’s death. Despite having fought against deep-rooted concepts (as the the immutability of species), Darwin accepted several other scientific concepts of his time — the inheritance of acquired characteristics being one of these.
The complete rejection of the inheritance of acquired characteristics by scientific community only took place in the early 20th century, thanks to the emergence of Mendelian paradigm. Mendel’s paradigm of inheritance, not Darwin’s evolutionary paradigm, opposes completely to the lamarckian paradigm: the ideas about use and disuse of body parts and its inheritance are relevant not only to evolution, but primarily to genetics. If we stop to think, we’ll realize that we criticize Lamarck chiefly because of his thoughts regarding genetics, not his thoughts regarding evolution — these are incorrect as well, but for entirely different reasons. Lamarckism (as taught in classrooms) is, therefore, a genetic hypothesis, and as such it will be beaten by Mendel’s paradigm, its biggest scientific antagonist (if we consider the way we teach Lamarck’s ideas in classroom, I must emphasize). In 1892, neo-Lamarckians suffered one of their toughest blows with the publication of Weismann’s works, whose ideas about germ line are genetic, not evolutionary.
The Russian case is much more obvious. T. D. Lysenko, the famous russian neo-Lamarckian with support of Stalin, didn’t combat directly evolutionary biologists: Instead, he persecuted the followers of Mendelian paradigm. One of his most important contemporary geneticists, N. I. Vavilov, was arrested and died in prison in 1943. The political persecution that Lysenko performed in the years of Stalin’s Government and, to a lesser extent, in the years of Khrushchev’s Government, added to the establishment of neo-lamarckism, seriously undermined the development of Russian biology.
Lamarck’s paradigm, with the inheritance of acquired characters, opposes to Mendelian paradigm, with the inheritance of factors responsible for determining the characters, and to Weismann’s, in which this inheritance depends on gametes only. Darwin, that has no relation with this clash of paradigms, will use at some points of his theoretical structure the inheritance of acquired characteristics, but always modulated by the ultimate force of natural selection, his great contribution.
From the works of Weismann, Sutton, de Vries, Morgan and others, the biology of the 20th century (Mayr, Dobzhansky, Fisher, Haldane, Wright …) removed the “use and disuse” component of evolutionary biology, among other changes, giving rise to a new evolutionary paradigm, that has changed even more since then. But that’s the nature of science.