The American Journal of Science and ArtsS. Converse, 1860 |
Dentro del libro
Resultados 1-5 de 98
Página 12
... less to any change effected by man upon it , that its annual extinction is due , but to causes that have no effect whatever upon its own constitution , and over which its constitutional peculiarities can exercise no control . 11. Again ...
... less to any change effected by man upon it , that its annual extinction is due , but to causes that have no effect whatever upon its own constitution , and over which its constitutional peculiarities can exercise no control . 11. Again ...
Página 15
... less well adapted to the locality , will yield less seed , and hence have fewer descendants . In the above operations Nature acts slowly on all organisms , but man does so rapidly on the few he cultivates or domesticates ; he selects an ...
... less well adapted to the locality , will yield less seed , and hence have fewer descendants . In the above operations Nature acts slowly on all organisms , but man does so rapidly on the few he cultivates or domesticates ; he selects an ...
Página 19
... less than an equal continental area possesses , and the relative numbers of species to genera ( or other higher groups ) is also much less than in similar continental areas . The further an island is from a continent , the smaller is ...
... less than an equal continental area possesses , and the relative numbers of species to genera ( or other higher groups ) is also much less than in similar continental areas . The further an island is from a continent , the smaller is ...
Página 21
... less for the contrasting one that the very commonest , most numerous , and universally dis- tributed Australian genera and species , as Casuarina , Eucalyp tus , Acacia , Boronia , Helichrysum , Melaleuca , etc. , and all the Australian ...
... less for the contrasting one that the very commonest , most numerous , and universally dis- tributed Australian genera and species , as Casuarina , Eucalyp tus , Acacia , Boronia , Helichrysum , Melaleuca , etc. , and all the Australian ...
Página 31
... less difficult or less meritorious . We need not then be surprised , if man arrived but tardily at the manufacture of iron and steel , which is still daily improving . In Carinthia traces of a most primitive method of producing iron ...
... less difficult or less meritorious . We need not then be surprised , if man arrived but tardily at the manufacture of iron and steel , which is still daily improving . In Carinthia traces of a most primitive method of producing iron ...
Contenido
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 | |
Otras ediciones - Ver todas
Términos y frases comunes
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
Pasajes populares
Página 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.
Página 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.
Página 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...
Página 154 - The limbs divided into great branches, and these into lesser and lesser branches, were themselves once, when the tree was...
Página 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.
Página 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.
Página 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.
Página 155 - ... in a fossil state. As we here and there see a thin straggling branch springing from a fork low down in a tree...
Página 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.
Página 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.