Ceylon Journal of Science: Botany, Volume 2

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University of Ceylon., 1905 - Botany

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Page 121 - The theory of natural selection might dispense with a restriction for which it is difficult to see either the need or the justification — namely, that the course of evolution always proceeds by steps that are severally minute, and that become effective only through accumulation.
Page 122 - Vries with regard to the actual origin of new species may be summed up as follows : Broadly speaking, species arise by mutation, by a sudden step in which either a single character or a whole set of characters together become changed.
Page 414 - ... between a tall and a semi-dwarf ("Satisfaction" and native No. 2) found in the F2 great variation in habit ranging from very robust to very feeble dwarf. Although he considers that there must be some sort of Mendelian segregation if the internodes are solely considered, he admits that "this cross seems to afford an example of remarkable intensification of both the allelomorphic characters of the same pair, namely tallness and dwarfness, the former in the FI and both in the F2 and later generations
Page 422 - On the growth of giant bamboos with special reference to the relation between conditions of moisture and the rate of growth.
Page 307 - ... the intermediate, indeed, is nearly always to be seen; in other cases, however, one of the two parental characters is so preponderant that it is difficult, or quite impossible, to detect the other in the hybrid.
Page 338 - Correns speaks of the characters as pcecilodynamous, a sufficiently expressive term. If, however, it were true that the pied condition is not really due to the dominance failing sometimes and succeeding sometimes, but to the existence in the mosaic of islands of the recessive character in the "paired" or unresolved state, we ought not to describe the phenomenon by reference to dominance at all. In the introduction to this paper reference was made to the case of Canary — Goldfinch mules. Here the...
Page 121 - ... dangerous, mutations must appear as often as useful ones, and have almost as much likelihood as these of persisting. 1 Species are discontinuous ; may not the variation by which species are produced, be discontinuous too ? p. 18. See also pp. 69, 568. BATESON'S conclusion is expressed in the following words : The evidence of variation suggests in brief, that the discontinuity of species results from the discontinuity of variation.
Page 303 - ... upon whom in this direction he made but little advance. C. Naudin's essay, entitled ' New Researches on Hybridity in Plants,' made its appearance in 1862. The author pointed out that the facts of the return of hybrids to the specific forms of their parents, when repeatedly crossed with the latter, are naturally explained by the hypothesis of the disjunction of the two specific essences in the pollen grains and ovules of the hybrid. The idea may, perhaps, be made somewhat clearer as follows :...
Page 351 - Mendel to remark that frequently " one of the parental characters was so preponderant that it was difficult or quite impossible to detect the other in the hybrid.
Page 45 - ... along each radius, per month during the three years in question. Timber. The genus Diospyros has obtained its widespread recognition mainly in virtue of the valuable timber yielded by several of its species. The term ebony is loosely applied to any black heavy wood capable of taking a good polish, and from time to time there has been considerable discussion as to the exact botanical source of the ebony of the ancients. Many plants are known to yield timber which in colour and density resembles...

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