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Página 137 - I by no means expect to convince experienced naturalists whose minds are stocked with a multitude of facts all viewed, during a long course of years, from a point of view directly opposite to mine. It is so easy to hide our ignorance under such expressions as the "plan of creation," "unity of design," &c., and to think that we give an explanation when we only re-state a fact.
Página 23 - Desmidieae,' a work which has greatly increased our knowledge of these obscure beings : " Freshwater figured, mucous, and microscopic Algt, of a green colour. Transverse division mostly complete, but in some genera incomplete. Cells or joints of two symmetrical valves, the junction always marked by the division of the endochrome, often also by a constriction. Sporangia formed by the coupling of the cells and union of their contents.
Página 140 - ... being occasionally hatched with a somewhat longer winglet, and a dwarfed stature ; on the probability of such a variety better adapting itself to the changing climate or other conditions than the old type — of such an origin of Alca...
Página 70 - ... given organism is in reality a true species. That is, it is not proved that some other form, which in the present state of knowledge we are constrained to suppose a distinct species, may not in truth be only a phase of variation, or of development, or an "alternation of generation " of the actual species, whose extremes of variation, or whose life history, are as yet unknown.
Página 129 - ... prennent constamment cette figure dans leur formation. Qu'on observe les petites écailles de la peau d'une roussette, on verra qu'elles sont hexagones, parce que chaque écaille croissant en même temps se fait obstacle et tend à occuper le plus d'espace qu'il est possible dans un...
Página 44 - A similar.process as to the transfer of the ova takes place in the fish as described in the last, with the exception that the males have no abdominal sac to enclose the ova. These fish, under favourable opportunities of calmness and of tides, may be seen side by side clinging with their tails to the tufts of Zostera marina, in which position the male is enabled to attach to the abdomen the ova, by the same influence of viscid secretion alluded to in the marsupial species.
Página 129 - On this subject I cannot do better than quote the words of Speaker Onslow, as given in one of his Notes on Burnet's History of his own Times.
Página 130 - ... toutes nécessairement hexagones par la compression réciproque. Chaque abeille cherche à occuper de même le plus d'espace possible dans un espace donné; il est donc nécessaire aussi, puisque le corps des abeilles est cylindrique , que leurs • cellules soient hexagones par la même raison des obstacles réciproques.
Página 70 - I would draw attention to a circumstance I am disposed to look upon as an almost unimpeachable argument as to their actual specific distinctness. I allude to the fact that, no matter how numerous or how few the fronds, the conjugating specimens always conjugate like form or species with like form or species — the abundant with their abundant neighbours of the same species, the rare seeking out the rare of the same species, and overlooking the possibly more numerous specimens of a perhaps closely...