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active adaptation adult advantage alimentary canal Amoeba animals ants appear attached become bees beginning birds body butterfly called carried cells changes close colony color complex composed depends differentiation digestive distinct divide division egg cells example existence eyes fact feed female finally fish function give grows habits hatched host increase individuals insects instinct interesting islands kinds known layer leaves less live lower male mass matter means mouth Nature nerve nest ocean opening organs outer parasites parent pass perform plants polyp possess primitive processes produced protective protoplasm Protozoa region reproduction resemblance rest seen sense shape side simple simplest animals single soon species sponge stage structure substance surface swimming taken tion true usually various Volvox wall whole wings workers worms young
Стр. 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. Even slow-breeding man has doubled in twenty-five years, and at this rate, in less than a thousand years, there would literally not be standing room for his progeny.
Стр. 215 - He cannot be mistaken for any other, and his flaming vest and blue stockings show that he does not court concealment. He is very abundant in the damp woods, and I was convinced he was uneatable so soon as I made his acquaintance and saw the happy sense of security with which he hopped about. I took a few specimens home with me, and tried my fowls and ducks with them ; but none would touch them. At last, by throwing down pieces of meat, for which there was a great competition amongst them, I managed...
Стр. 20 - ... inhabitants of the water has followed a roundabout path from the surface to the bottom and then back into the water. When this fact is seen in all its bearings and its full significance is grasped, it is certainly one of the most notable and instructive features of evolution. The food-supply of marine animals consists of a few species of microscopic organisms which are inexhaustible and the only source of food for all the inhabitants of the ocean.
Стр. 116 - The elephant is reckoned the slowest breeder of all known animals, and I have taken some pains to estimate its probable minimum rate of natural increase; it will be safest to assume that it begins breeding when thirty years old, and goes on breeding till ninety years old, bringing forth six young in the interval, and surviving till one hundred years old ; if this be so, after a period of from 740 to 750 years there would be nearly nineteen million elephants alive, descended from the first pair.