Animal Studies: A Text-book of Elementary Zoology for Use in High Schools and CollegesD. Appleton, 1903 - 459 páginas |
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Página 35
... per- forate the body wall , a skeleton is developed , and the char- acteristic features of the adult are thus attained . 34. Distribution . - The sponges are aquatic animals , THE SLIGHTLY COMPLEX ANIMALS OR SPONGES 35.
... per- forate the body wall , a skeleton is developed , and the char- acteristic features of the adult are thus attained . 34. Distribution . - The sponges are aquatic animals , THE SLIGHTLY COMPLEX ANIMALS OR SPONGES 35.
Página 42
... adult ; and , so far as we know , all the many - celled ani- mals in their growth from the egg repeat more or less clearly the stages passed through by their forefathers . CHAPTER V THE CŒLENTERATES 39. General remarks . - This 42 ...
... adult ; and , so far as we know , all the many - celled ani- mals in their growth from the egg repeat more or less clearly the stages passed through by their forefathers . CHAPTER V THE CŒLENTERATES 39. General remarks . - This 42 ...
Página 53
... adult . As growth pro- ceeds , however , it un- FIG . 26. - An attached scyphozoan jelly - fish ( Haliclystus ) . Natural size , from Nature . dergoes a series of transformations which result in the adult form . 50. Sea - anemones ...
... adult . As growth pro- ceeds , however , it un- FIG . 26. - An attached scyphozoan jelly - fish ( Haliclystus ) . Natural size , from Nature . dergoes a series of transformations which result in the adult form . 50. Sea - anemones ...
Página 65
... adult . The life cycle is now complete ; the young form has found a new host ; and the process shows how wonderfully animals are adapted to the conditions which surround them , and how closely they must conform to these conditions in ...
... adult . The life cycle is now complete ; the young form has found a new host ; and the process shows how wonderfully animals are adapted to the conditions which surround them , and how closely they must conform to these conditions in ...
Página 67
... adult . In other species a similar process results in the formation of a chain of six individuals , placed end to end , the chain finally breaking up into as many complete worms . It is possible that the tapeworm may also be looked upon ...
... adult . In other species a similar process results in the formation of a chain of six individuals , placed end to end , the chain finally breaking up into as many complete worms . It is possible that the tapeworm may also be looked upon ...
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Palavras e frases frequentes
adapted adult Amaba amphibians animals annelids ants appearance Arthropods attached bear become bees birds body brain burrow butterfly called canal cavity cells chitin clams color common crabs crayfishes crinoids Crustacea digestive dorsal earthworm eggs enemies exist external eyes feed feet female fins fishes flagellum flatworms forms fossils fresh-water frogs gastrula gills habits hatched head highly individuals insects instinct intestine jelly-fish known lancelet larva larvæ legs less limbs live lizards male mals mammals matter mollusks mouth muscles natural nerve nest notochord organs oxygen pair parasites parent plants plates possess prey protective resemblance Protozoa pupa regions relatively reptiles rocks Sacculina salamanders sand segments shell side skeleton skin smell snails snakes special sense species spines sponge squirrel stage starfishes stomach structure substance surface surroundings swimming tail teeth tion tree 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...