Gärtner by the results of these transformation experiments, was led to oppose the opinion of those naturalists who dispute the stability of plant species and believe in a continuous evolution of vegetation. He perceives in the complete transformation of one species into another an indubitable proof that species are fixed within limits beyond which they cannot change. Although this opinion cannot be unconditionally accepted, we find on the other hand in Gartner's experiments a noteworthy confirmation of that supposition regarding variability of cultivated plants which has already been expressed.
Gregor MendelRelated topics
believe beyond change confirmation evolution find indubitable led noteworthy opinion plant proof stability supposition transformation variability vegetationRelated quotes
There isn't any room,” said Joshua. "You travel back along the line of time and you don't find the past, but another world, another bracket of consciousness. The earth would be the same, you see, or almost the same. Same trees, same rivers, same hills, but it wouldn't be the world we know. Because it has lived a different life, it has developed differently. The second back of us is not the second back of us at all, but another second, a totally separate sector of time. We live in the same second all the time. We move along within the bracket of that second, that tiny bit of time that has been allotted to our particular world.
Clifford D. Simak
The French botanist and chemist Henri-Louis Duhamel de Monceau (1700–1782) identified a fungal disease on the bulbs of saffron crocus (now named Helicobasidium purpureum) and illustrated its sclerotia on the bulbs. His report was read to the Academie royale des Sciences in April 1728; it was "wellconceived, thorough, and conclusive, and led to his election as adjoint chimiste in the same year” (Eklund 1971:223). Duhamel discovered that this fungus spreads underground from one bulb to another. In his Éléments d'agriculture (two volumes, 1762; English edition, 1764), he also accepted insects as a cause of some plant diseases.
Henri-Louis Duhamel du Monceau
The theory of the origin of new species by variation will also explain why a species which has once died out never reappears, and why the fossil fauna and flora recede farther and farther from the living type in proportion as we trace it back to remoter ages. It would also account for the fact, that when we have to intercalate a new set of fossiliferous strata between two groups previously known, the newly discovered fossils serve to fill up gaps between specific or generic types previously familiar to us, supplying often the missing links of the chain, which, if transmutation is accepted, must once have been continuous.
Charles Lyell
Evolution in... cases has clearly been a very slow and almost (if not quite) continuous process, exactly as Darwin had predicted.
We must remember, however, that the organisms studied in this way are far from representative. They are in general the most successful members of animal associations living in very constant marine or lacustrine environments. We have not got similar data for land species... Nor do we possess them for the rarer forms. We shall see... that perhaps dominant species in a uniform environment are the least likely to undergo sudden change to a new type.
J. B. S. Haldane
Darwin believed that the crossing of two types generally led to a blend, and that consequently bisexual reproduction tended to make a species uniform. He therefore had to postulate some cause constantly at work to keep up the inheritable variation within a species. He very naturally looked to the effects of differences of environment. ...It was shown that Darwin had been wrong in supposing that variations due to environment were inheritable. Selection merely picked out the best available line from a given population, and would not, as Darwin had believed, give rise to an unlimited amount of change.
J. B. S. Haldane