Animal Studies: A Text-book of Elementary Zoology for Use in High Schools and CollegesD. Appleton, 1903 - 459 páginas |
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Página 31
... pairs temporarily or permanently , exchange nu- clear material , and separate again with apparently renewed energy and the ability to divide for many generations . 31. Simple and complex animals . — It is important to note that these ...
... pairs temporarily or permanently , exchange nu- clear material , and separate again with apparently renewed energy and the ability to divide for many generations . 31. Simple and complex animals . — It is important to note that these ...
Página 74
... pair of kidneys to every segment ( Figs . 40 , 41 ) . worm kidney . b , blood- vessel ; f , funnel open- ing into body cavity ; o , outer opening ; 8 , septum ; w , body wall . Each consists of a coiled tube wrapped in a mass of small ...
... pair of kidneys to every segment ( Figs . 40 , 41 ) . worm kidney . b , blood- vessel ; f , funnel open- ing into body cavity ; o , outer opening ; 8 , septum ; w , body wall . Each consists of a coiled tube wrapped in a mass of small ...
Página 77
... pair of lateral plates ( Figs . 41 , 42 , B ) or paddles with many lobes , some of which bear numerous bristles . By a to - and - fro movement these organs aid in pushing the animal about , or may enable certain spe- cies to swim with ...
... pair of lateral plates ( Figs . 41 , 42 , B ) or paddles with many lobes , some of which bear numerous bristles . By a to - and - fro movement these organs aid in pushing the animal about , or may enable certain spe- cies to swim with ...
Página 81
... pairs of simple eyes are borne on the head , and owing to the fact that they are active swimmers , or move by caterpillar - like looping , loco- motor spines are unnecessary and absent . In their internal organization , however , there ...
... pairs of simple eyes are borne on the head , and owing to the fact that they are active swimmers , or move by caterpillar - like looping , loco- motor spines are unnecessary and absent . In their internal organization , however , there ...
Página 98
... pairs of tentacles , one of which carries the eyes . On the right side of the animal , some distance behind the head , is the opening of the little sac - like mantle cavity ( Fig . 54 ) which contains the respiratory organs , and into ...
... pairs of tentacles , one of which carries the eyes . On the right side of the animal , some distance behind the head , is the opening of the little sac - like mantle cavity ( Fig . 54 ) which contains the respiratory organs , and into ...
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Palavras e frases frequentes
adapted adult alimentary canal Amaba amphibians animals annelids ants appearance appendages Arthropods attached bear become bees birds body burrow butterfly canal cavity cells chitin cilia clams colony color common consists crabs crayfishes crinoids Crustacea digestive dorsal earthworm eggs enemies exist external eyes feed feet female fins fishes flagellum flatworms forms fresh-water frogs gastrula gills habits hatched head highly host individuals insects instinct intestine jelly-fish kinds of animals known lancelet larva larvæ legs limbs live lizards male mals mammals mollusks mouth muscles natural nerve nest notochord organs oxygen pair parasites parent plants plates possess prey protection Protozoa pupa queen relatively reptiles resemblance rocks Sacculina salamanders segments sense shell side skeleton skin snails species spines sponge squirrel stage stomach structure substance surface surroundings swimming tail teeth tentacles tion usually various vertebrates wings workers worms young
Passagens conhecidas
Página 282 - 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.
Página 211 - Its summer plumage so exactly harmonizes with the lichen-coloured stones among which it delights to sit, that a person may walk through a flock of them without seeing a single bird; while in winter its white plumage is an almost equal protection.
Página 264 - Fig. 41 are indistinguishably alike, but one embryo is sure to develop into a fish and the other into a salamander. This certainty of an embryo to become an individual of a certain kind is called the law of heredity.
Página 343 - Tremex burrow is reached she deposits an egg in it. The larva that hatches from this egg creeps along this burrow until it reaches its victim, and then fastens itself to the horntail larva, which it destroys by sucking its blood. The larva of...
Página 362 - 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...
Página 329 - Steppes, he once saw an eagle belonging to an altogether gregarious species (the white-tailed eagle, jfaliaetos albicilla) rising high in the air ; for half an hour it was describing its wide circles in silence when at once its piercing voice was heard. Its cry was soon answered by another eagle which approached it, and was followed by a third, a fourth, and so on, till nine or ten eagles came together and soon disappeared.
Página 283 - 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.
Página 363 - There are two intensely black spots on this margin in the appropriate position for eyes, and the whole appearance is that of a large flat face extending to the outer edge of the red margin. The effect is an intensely exaggerated caricature of a vertebrate face, which is probably alarming to the vertebrate enemies of the caterpillar. . . . The effect is also greatly strengthened by two pink whips which are swiftly protruded from the prongs of the fork in which the body terminates. . . . The end of...