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action amphibians ancestor animals and plants apes Ascidians atoms become beginning birds body bones brain breeds called catarrhine cells changes chemical chimpanzee common compound corpus callosum Darwin descended developed difficulty distinct doctrine of Evolution earth eggs elements embryo environment Eocene Evolutionist existence extinct fact favourable feet fish fissure force fore limbs groups Haeckel Hippus human important individuals inorganic insects instance instinct kind lancelet lemur less light living forms living things lobe lower lowest mammals marsupials matter means modified monkeys monotremes motion muscles Natural Selection nerve notochord offspring organs Origin of Species parent period pithecanthropus erectus plants and animals platyrrhine pliocene posterior horn primates produced Professor protoplasm races reptiles sagittal crest says seen skin skull Spencer stage structure struggle substance swimbladder tail teeth theory tion tissue toes universe variations varieties vertebrates whole
Page 115 - 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.
Page 114 - I use this term in a large and metaphorical sense including dependence of one being on another, and including (which is more important) not only the life of the individual, but success in leaving progeny. Two canine animals, in a time of dearth, may be truly said to struggle with each other which shall get food and live. But a plant on the edge of a desert is said to struggle for life against the drought, though more properly it should be said to be dependent on the moisture.
Page 116 - In looking at Nature, it is most necessary to keep the foregoing considerations always in mind — never to forget that every single organic being around us may be said to be striving to the utmost to increase in numbers...
Page 116 - I marked all the seedlings of our native weeds as they came up, and out of 357 no less than 295 were destroyed, chiefly by slugs and insects. If turf which has long been mown, and the case would be the same with turf closely browsed by quadrupeds, be let to grow, the more vigorous plants gradually kill the less...
Page 197 - is a definite combination of heterogeneous changes, both simultaneous and successive, in correspondence with external coexistences and sequences.
Page 116 - If turf which has long been mown, and the case would be the same with turf closely browsed by quadrupeds, be let to grow, the more vigorous plants gradually kill the less vigorous, though fully grown plants; thus out of twenty species growing on a little plot of mown turf (three feet by four) nine species perished, from the other species being allowed to grow up freely.
Page 103 - Domestication,' there are two factors: namely, the nature of the organism, and the nature of the conditions. The former seems to be much the more important; for nearly similar variations sometimes arise under, as far as we can judge, dissimilar conditions; and, on the other hand, dissimilar variations arise under conditions which appear to be nearly uniform.
Page 191 - Evolution is an integration of matter and concomitant dissipation of motion ; during which the matter passes from an indefinite, incoherent homogeneity to a definite, coherent heterogeneity, and during which the retained motion undergoes a parallel transformation.
Page 152 - ... and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist ; if, further, the eye does vary ever so slightly, and the variations be inherited, which is certainly the case ; and if any variation or modification in the organ be ever useful to an animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered...
Page 158 - MANY instincts are so wonderful that their development will probably appear to the reader a difficulty sufficient to overthrow my whole theory. I may here premise, that I have nothing to do with the origin of the mental powers, any more than I have with that of life itself.