Darwin's Hypothesis Research Articles

Nickel for Your Thoughts: Urey and the Origin of the Moon

The theories of Harold C. Urey (1893-1981) on the origin of the moon are discussed in relation to earlier ideas, especially George Howard Darwin's fission hypothesis. Urey's espousal of the idea that the moon had been captured by the earth and has preserved information about the earliest history of the solar system led him to advocate a manned lunar landing. Results from the Apollo missions, in particular the deficiency of siderophile elements in the lunar crust, led him to abandon the capture selenogony and tentatively adopt the fission hypothesis.

Capture Enhancement in a Carnivorous Aquatic Plant: Function of Antennae and Bristles in Utricularia vulgaris

Traps of the carnivorous hydrophyte Utricularia vulgaris Linnaeus (Lentibulariaceae) have structures termed antennae and bristles around their trapdoors that increase their rate of entrapment of the substrate-dwelling prey Chydorus sphaericus (Chydoridae, Crustacea). The kind and number of these structures are important in determining capture rate. Experimental data and corresponding behavioral observations support Darwin's hypothesis that antennae and bristles function as a "funnel" leading potential prey toward the trapdoor and their capture by offering the prey a favorable substrate that exploits their natural locomotor and feeding behavior.

Pollen flow in a population of Primula vulgaris Huds.

A British population of Primula vulgaris was visited four times between 1971 and 1976 for study of the nature and functioning of distyly. The stainability and production of pollen from pins exceeded those of thrums. About 20% of pin pollen and 48% of thrum pollen was removed from anthers by insect visitors. Pins and thrums were present in a 1:1 ratio in 1971 but pins outnumbered thrums in 1976. Thrums produced more seeds per flower than pins though the number of ovules produced by each was similar. Two methods for collecting stigmas from open flowers and analyzing them for pollen loans produced somewhat different results. For pin stigmas, the pollen load consisted of 2–23% thrum pollen; for thrum stigmas, the pollen load consisted of 0–71% pin pollen with most stigmas having less than 50% pin pollen. In general, intermorph pollen flow is less than would be expected if pollen flow were random. It is probable that most intramorph pollen on stigmas is a result of self- or geitonogamous pollination. The extensive literature concerning the natural pollinators of the primrose is reviewed. Although Darwin's hypothesis concerning the functional significance of distyly in promoting intermorph pollination was never quantified, the pollen flow patterns observed in P. vulgaris are unexpectedly deviant and are similar to those patterns observed in several unrelated heterostylous species in other plant families.

J. F. M. DOVASTON, AN OVERLOOKED PIONEER OF FIELD ORNITHOLOGY

scan the frankly popular and apparently quite ephemeral matter so often contained in them. The journal in this instance is Loudon's Magazine ofNatural History, which began in May 1828, appearing at first bimonthly, price 3s. 6d. It was aimed originally at young people, but soon began to attract such a large following among naturalists of all ages and became so generally read that by 1835 it had turned into a medium for quite substantial scientific papers of wide general interest. In its pages in that year, for example, were published the important speculations of Edward Blyth, recently claimed as a crucial yet unacknowledged source of Darwin's main evolutionary hypotheses.2 Previous to this more learned period, however, there were many contributions of a light-hearted or

An origin of the Moon by rotational fission during formation of the Earth's core

Darwin's hypothesis of lunar origin from a rapidly rotating earth can be modified by substitution of excessive rotation rate and unstable spin driven by conservation of angular momentum during formation of the earth's core for Darwin's now discredited tidal resonance mechanism. Criticisms which caused rejection of the older hypothesis are considered in the light of this modification and of subsequent discoveries and ideas. Most severe is lack of angular momentum in the present earth-moon system, a criticism which is itself open to question in terms of possible magnetic frictions during the early history of the solar system; observed but presently unexplainable components in rate of change in rotation of the earth; possible changes in diameter of the earth with time. Among the explanations provided by the hypothesis are relatively circular lunar orbit, specific gravity of the moon, apparent nonhydrostatic figure of the moon, constant face toward the earth, and gross sequence of geologic events recorded on the lunar face. Several proposed tests of the hypothesis should soon be possible. Until more data become available, it is suggested that a lunar birth from the earth be reinstated among our current working hypotheses.

Hugo de Vries and the Gene Concept

In several of the jubilee publications on Darwinism it is accepted as established that Darwin's original hypothesis of natural selection could be transformed into a sound basis of neo-Darwinism only after Darwin's vague and partly erroneous views on heredity, as expressed in his "provisional hypothesis of pangenesis," were replaced by the modern theory of heredity based on Mendel's laws. In this lecture, I have tried to show that the fundamental rectifications of Darwin's theory were already provided in 1889 by Hugo de Vries in his book "Intracellulare Pangenesis." The influence of these conceptions of Hugo de Vries on the gradual development of theoretical insight into genetics, evolution and the species-concept has been expounded.

Use in Plant Ecology of Causation, Physiology and a Definition of Vegetation

Use in Plant Ecology of Causation, Physiology and a Definition of Vegetation

Friedenthal's Experimental Proof of Blood-Relationship

IN recent years important evidence in favor of Darwin's theory of the descent of man has increased. Eutg^en Dubois found in PI//ecazi//iropits crtiaus the much-sought-for missing link between man and living anthropoid apes. Selenka has shown that, of the catarrhine apes, the living anthropoid apes resemble man in having a placenta discoidalis capsularis, while all other catarrhines have a placenta bidiscoiclalis. Ernst Haeckel has accumulated evidence showing that man has descended from a line of extinct catarrhincs whose immediate ancestors belonged to the group of tailless anthropoid apes, and whose more remote ancestors belonged to the Cynopithecili. The evidence afforded by comparative paleontology, comparative embryology, and comparative anatomy agrees in supporting Darwin's hypothesis. To all this evidence is now added evidence dependingupon the similarity in chemical composition of the blood of closely related animals. Comparative chemical analyses of blood are attended with great difficulties because of variations in the blood depending upon the varying conditions of nutrition in the animal. Landois, in his researches on the effects of animal blood transfusions upon human diseases, attributed his failures, so far as the beneficial effects of the blood transfusion upon the disease were concerned, to the dissolving of the red blood corpuscles of the injected blood by the blood of the recipient. Experiments upon lower animals, in the way of injecting blood from some animal of a remote species, led to the same results as the experiments upon man. The animals

The Life and Letters of George John Romanes

THE life of most men of science is uneventful so far as the rest of the world is concerned, and can hardly interest more than the circle of personal friends. And the letters of men of science also have, as a rule, but a limited interest. Any scientific information which they contain has usually been published elsewhere, and if of importance, is already familiar to the scientific reader. The account of the life, and the selection of the letters of George Romanes, which is here presented, offer in some measure an exception to the general rule, for they contain matters which will keenly interest others than those who may desire to follow merely the scientific career of the man. But it is the scientific correspondence which will, without doubt, be that which will chiefly interest the readers of NATURE, and it is this, therefore, with which alone we propose here to deal. And of the scientific correspondence, that which Romanes carried on with Charles Darwin during a period of nine years would alone furnish enough interest to ensure a cordial welcome to this work. For Mrs. Romanes has not confined herself, as is so often done by the biographer, to presenting only the one side of a correspondence, but has wisely decided in this and certain other instances to allow both sides to appear, far more than doubling thereby its value and interest. And since, with one exception, none of these letters of Darwin have hitherto been given to the world, and moreover he seems in them to have opened up his heart with the frankest confidence to the young devotee whose powers of thought he was one of the first to recognise, it is obvious that this correspondence must have an altogether exceptional interest. It deals mainly, as might be supposed, with subjects bearing on the question of inheritance, and especially with Darwin's hypothesis of Pangenesis. In attempts to prove this theory, Romanes devoted an immense amount of time in patient experimentation, but as the experiments yielded for the most part a negative result, showing neither for nor against the hypothesis, they were never systematically published. On this account the descriptions of some of these experiments, which are here given at length, will be welcomed by those who may be carrying on similar work in the future. The subject was one upon which Romanes was “keen” to the very last, and almost the latest experiments which he planned, had a direct bearing upon the doctrine in question. And even when his time was fully occupied with the fascinating experiments upon Medusae, by which he first found fame as a scientific inquirer, he was able to devote attention to the carrying out of laborious work on this subject. In July 1875, he writes to Darwin: The Life and Letters of George John Romanes. Written and edited by his Wife. Pp. viii + 360. (London: Longmans, Green, and Co., 1896.)

On Evolution and Man's Place in Nature

My aim in this paper will be to present as concisely as possible the problems involved in Man's Place in Nature, and to consider briefly how far an evolution theory contributes towards the solution of these problems.Needful preliminaries can be disposed of briefly. We are agreed that evolution is “a change from an indefinite, incoherent homogeneity to a definite, coherent heterogeneity, through continuous differentiations and integrations.” We are agreed that this process is to be taken as applicable in the history of matter and motion, and afterwards in the history of organised existence, raising the whole problem of biology. We do not require here to linger over the transition from the one to the other, as all requirements are met by accepting life and its laws as facts, and acquiescing in Darwin's hypothesis of one or more primordial germs.

Mr. Darwin's Hypothesis of Pangenesis as Applied to the Faculty of Memory

Mr. Darwin's Hypothesis of Pangenesis as Applied to the Faculty of Memory

On Mr. Darwin's Hypothesis of Pangenesis as Applied to the Faculty of Memory [Abstract and Comments

On Mr. Darwin's Hypothesis of Pangenesis as Applied to the Faculty of Memory [Abstract and Comments