The American Journal of Science and ArtsS. Converse, 1860 |
Результаты поиска по книге
Результаты 1 – 5 из 61
Стр. 4
... varieties , the time required to produce wide variations from any given specific type is so great , and the number of species and varieties known to propagate for indefi . nite periods a succession of absolutely identical members is so ...
... varieties , the time required to produce wide variations from any given specific type is so great , and the number of species and varieties known to propagate for indefi . nite periods a succession of absolutely identical members is so ...
Стр. 5
... varieties , or than species are into limitable genera or groups of higher value , and that the relationships of species are transmitted he- reditarily in a very eminent degree , are the strongest appear- ances in favor of species being ...
... varieties , or than species are into limitable genera or groups of higher value , and that the relationships of species are transmitted he- reditarily in a very eminent degree , are the strongest appear- ances in favor of species being ...
Стр. 6
... varieties of a species common to both , nor are the species of any two countries alike in number and kind . 2. The rate at which plants vary is always slow , and the ex- tent or degree of variation is graduated . Sports even in color ...
... varieties of a species common to both , nor are the species of any two countries alike in number and kind . 2. The rate at which plants vary is always slow , and the ex- tent or degree of variation is graduated . Sports even in color ...
Стр. 7
... varieties , so some of the most naturalt and limitable orders * Mr. Darwin , after a very laborious analysis of many Floras , finds that the spe- cies of large genera are relatively more variable than those of small ; a result which I ...
... varieties , so some of the most naturalt and limitable orders * Mr. Darwin , after a very laborious analysis of many Floras , finds that the spe- cies of large genera are relatively more variable than those of small ; a result which I ...
Стр. 8
... varieties , it will present a group of species with complex relations inter se ; if , on the contrary , it is numerically decreasing , such decrease must lead to the extinction of some varieties , and hence result in the better ...
... varieties , it will present a group of species with complex relations inter se ; if , on the contrary , it is numerically decreasing , such decrease must lead to the extinction of some varieties , and hence result in the better ...
Содержание
1 | |
25 | |
33 | |
43 | |
49 | |
62 | |
68 | |
79 | |
14 | |
32 | |
42 | |
52 | |
62 | |
74 | |
100 | |
92 | |
111 | |
114 | |
126 | |
139 | |
142 | |
146 | |
153 | |
185 | |
199 | |
205 | |
218 | |
248 | |
268 | |
276 | |
282 | |
294 | |
300 | |
326 | |
335 | |
346 | |
361 | |
383 | |
400 | |
414 | |
421 | |
427 | |
434 | |
441 | |
447 | |
103 | |
112 | |
121 | |
129 | |
138 | |
155 | |
161 | |
182 | |
194 | |
204 | |
217 | |
226 | |
240 | |
253 | |
264 | |
313 | |
329 | |
337 | |
361 | |
367 | |
385 | |
391 | |
399 | |
409 | |
415 | |
424 | |
434 | |
455 | |
465 | |
472 | |
Другие издания - Просмотреть все
Часто встречающиеся слова и выражения
acid Alethopteris American animals antimony appears arsenic atomic atomic weight aurora axis ball bismuth Brgt bright carbon carbonic acid Carboniferous character chemical clouds coal coast color containing Cretaceous crystals described determined diameter Dicotyledons direction east existence extended fact feet flame flora fossil genera genus geological give Gulf Stream heat horizon inches Jour Journal Lake Lepidodendron less light limestone Lsqx mass matter means metals meteor miles mineral motion mountains natural nearly nebular hypothesis Neuropteris northern observations obtained organic origin osmium oxyd oxygen Pecopteris peculiar phenomena plants plates platinum portion potash present produced Prof relations remarkable river rocks ruthenium sandstone scientific SECOND SERIES seen Sept shales species specimens Sphenopteris strata stream streamers substance supposed surface temperature theory thickness tion variation varieties vegetation velocity whole zenith
Популярные отрывки
Стр. 172 - I cannot doubt that the theory of descent with modification embraces all the members of the same great class or kingdom. I believe that animals are descended from at most only four or five progenitors, and plants from an equal or lesser number.
Стр. 144 - As all the living forms of life are the lineal descendants of those which lived long before the Cambrian epoch, we may feel certain that the ordinary succession by generation has never once been broken, and that no cataclysm has desolated the whole world. Hence we may look with some confidence to a secure future of great length. And as natural selection works solely by and for the good of each being, all corporeal and mental endowments will tend to progress towards perfection.
Стр. 143 - Judging from the past, we may safely infer that not one living species will transmit its unaltered likeness to a distant futurity. And of the species now living very few will transmit progeny of any kind to a far distant futurity...
Стр. 154 - The limbs divided into great branches, and these into lesser and lesser branches, were themselves once, when the tree was...
Стр. 166 - There is no exception to the rule that every organic being naturally increases at so high a rate that, if not destroyed, the earth would soon be covered by the progeny of a single pair.
Стр. 166 - Nothing is easier than to admit in words the truth of the universal struggle for life, or more difficult — at least I have found it so — than constantly to bear this conclusion in mind.
Стр. 170 - But if variations useful to any organic being ever do occur, assuredly individuals thus characterised will have the best chance of being preserved in the struggle for life ; and from the strong principle of inheritance, these will tend to produce offspring similarly characterised. This principle of preservation, or the survival of the fittest, I have called Natural Selection.
Стр. 155 - ... in a fossil state. As we here and there see a thin straggling branch springing from a fork low down in a tree...
Стр. 445 - THE BOYDEN PREMIUM URIAH A. BOYDEN, ESQ., of Boston, Mass., has deposited with THE FRANKLIN INSTITUTE the sum of one thousand dollars, to be awarded as a premium to "Any resident of North America who shall determine by experiment whether all rays of light,* and other physical rays, are or are not transmitted with the same velocity.
Стр. 154 - The green and budding twigs may represent existing species ; and those produced during former years may represent the long succession of extinct species. At each period of growth all the growing twigs have tried to branch out on all sides, and to overtop and kill the surrounding twigs and branches, in the same manner as species and groups of species have at all times overmastered other species in the great battle for life.