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Inhaltsangabe: This historic book may have numerous typos, missing text or index. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. 1909. Not illustrated. Excerpt: ... chapter vi Difficulties Of The Theory Difficulties of the theory of descent with modification--Absence or rarity of transitional varieties--Transitions in habits of life--Diversified habits in the same species--Species with habits widely different from those of their allies--Organs of extreme perfection--Modes of transition--Cases of difficulty--Natura non facit saltum--Organs of small importance--Organs not in all cases absolutely perfect--The law of Unity of Type and of the Conditions of Existence embraced by the theory of Natural Selection. long before the reader has arrived at this part of my work, a crowd of difficulties will have occurred to him. Some of them are so serious that to this day I can hardly reflect on them without being in some degree staggered; but, to the best of my judgment, the greater number are only apparent, and those that are real are not, I think, fatal to theory. These difficulties and objections may be classed under the following heads:--First, why, if species have descended from other species by fine gradations, do we not everywhere see innumerable transitional forms? Why is not all nature in confusion, instead of the species being, as we see them, well defined? Secondly, is it possible that an animal having, for instance, the structure and habits of a bat, could have been formed by the modification of some other animal with widely different habits and structure? Can we believe that natural selection could produce, on the one hand, an organ of trifling importance, such as the tail of a giraffe, which serves as a flyflapper, and, on the other hand, an organ so wonderful as the eye? Thirdly, can instincts be acquired and modified through natural selection? What shall we say to the instinct which leads the bee to make cells, and which...
Inhaltsangabe: This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1882 edition. Excerpt: ...working circularly as they deepen each cell. They do not make the whole three-sided pyramidal base of any one cell at the same time, but only that one rhombic plate which stands on the extreme growing margin, or the two plates, as the case may be; and they never complete the upper edges of the rhombic plates, until the hexagonal walls are commenced. Some of these statements differ from those made by the justly celebrated elder Huber, hut I am convinced of their accuracy; and if I had space, I could show that they are conformable with my theory. Huber's statement, that the very first cell is excavated out of a little parallel-sided wall of wax, is not, as far as I have seen, strictly correct; the first commencement having always been a little hood of wax; but I will not here enter on details. We see how important a part excavation plays in the construction of the cells; but it would be a great error to suppose that the bees cannot build up a rough wall of wax in the proper position--that is, along the piane of intersection between two adjoining spheres. I have several specimens showing clearly that they can do this. Even in the rude circumferential rim or wall of wax round a growing comb, flexures may sometimes be observed, corresponding in position to the planes of the rhombic basal plates of future cells. But the rough wall of wax has in every case to be finished off, by being largely gnawed away on both sides. The manner in which the bees build is curious; they always make the first rough wall from ten to twenty times thicker than the excessively thin finished wall of the cell, which will ultimately be left. We shall understand how they work, by supposing masons first to pile up a broad ridge of cement, and then to bein cutting it away equally...
Buchbeschreibung Paperback. Buchzustand: Very Good. The book has been read, but is in excellent condition. Pages are intact and not marred by notes or highlighting. The spine remains undamaged. Buchnummer des Verkäufers GOR002353459
Buchbeschreibung Random House Value Publishing. Hardcover. Buchzustand: Good. Ex-Library Book - will contain Library Markings. Light shelving wear with minimal damage to cover and bindings. Pages show minor use. Buchnummer des Verkäufers G0517309777I3N10
Buchbeschreibung AVENEL. Hardcover. Buchzustand: GOOD. book was well loved but cared for. Possible ex-library copy with all the usual markings and stickers. Some light textual notes, highlighting and underling. Buchnummer des Verkäufers 2758649445
Buchbeschreibung Paperback. Buchzustand: Good. Buchnummer des Verkäufers TT01452971B
Buchbeschreibung AVENEL. Hardcover. Buchzustand: Good. 0517309777 Good Condition. Five star seller - Buy with confidence!. Buchnummer des Verkäufers Z0517309777Z3
Buchbeschreibung Buchzustand: good. 885 Gramm. Buchnummer des Verkäufers M00517309777-G
Buchbeschreibung AVENEL, 1979. Hardcover. Buchzustand: Used: Very Good. Buchnummer des Verkäufers SONG0517309777
Buchbeschreibung Buchzustand: Good. Book Condition: Good. Buchnummer des Verkäufers 97805173097734.0
Buchbeschreibung Avenel, New York, 1979. Hardcover. Buchzustand: Book: Good. 5th ptg.. 8vo. 476 pp. 6 1/8 x 9 1/8. Dark green leatherette covered boards, stamped in gold on front and spine. No dj. Light bumping to edges; no markings noted. Buchnummer des Verkäufers 95849
Buchbeschreibung AVENEL, 1979. Hardcover. Buchzustand: Used: Good. Buchnummer des Verkäufers 14069003