Animal studiesD. Appleton and Company, 1903 - 459 páginas |
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Página 84
... teeth located there . In the absence of a circulatory system the absorbed food is conveyed by the fluid of the body - cavity , which also con- veys the wastes to the delicate kidneys . Several other features of their organization are of ...
... teeth located there . In the absence of a circulatory system the absorbed food is conveyed by the fluid of the body - cavity , which also con- veys the wastes to the delicate kidneys . Several other features of their organization are of ...
Página 92
... teeth like a rasp , which gradually enlarge the cavity as the animal grows , until it becomes a prisoner with no means of communication with the exterior save the small opening through which the siphons project . This is also the case ...
... teeth like a rasp , which gradually enlarge the cavity as the animal grows , until it becomes a prisoner with no means of communication with the exterior save the small opening through which the siphons project . This is also the case ...
Página 97
... teeth . These are often readily obtained , sometimes as they are escaping from the parent , and when examined under the microscope are seen to rapidly open and close their shells in a snapping fashion when in the least disturbed . In a ...
... teeth . These are often readily obtained , sometimes as they are escaping from the parent , and when examined under the microscope are seen to rapidly open and close their shells in a snapping fashion when in the least disturbed . In a ...
Página 101
... teeth in our land forms ( Fig . 57 ) , while in certain marine snails they are beyond computation . With the licking motion of the tongue this rasp tears the food into shreds before it is swallowed , and in the whelks or borers it ...
... teeth in our land forms ( Fig . 57 ) , while in certain marine snails they are beyond computation . With the licking motion of the tongue this rasp tears the food into shreds before it is swallowed , and in the whelks or borers it ...
Página 123
... teeth operated by powerful muscles will be noted , and beyond these a strainer consisting of many closely set hairs . In operation this " gastric mill " takes the food passed on from the mouth - parts , and crushes and tears it until ...
... teeth operated by powerful muscles will be noted , and beyond these a strainer consisting of many closely set hairs . In operation this " gastric mill " takes the food passed on from the mouth - parts , and crushes and tears it until ...
Palavras e frases frequentes
adapted adult Amaba amphibians animals annelids ants appearance Arthropods attached bear become bees birds blood body brain burrow butterfly called canal cavity cells chitin cilia 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 greater number habits hatched head highly individuals insects instinct intestine jelly-fish known lancelet larva larvæ legs less limbs live lizards male mals mammals mollusks mouth muscles natural nerve nest notochord organs oxygen pair parasites parent plants 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 stomach structure substance surface surroundings swimming tail teeth tentacles tion tree usually various vertebrates wings workers worms young
Passagens conhecidas
Página 278 - 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 207 - 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 381 - Many lowly organized animals, as some polyps, and worms, have certain cells of the skin specially provided with pigment. These cells grouped together form what is called a pigment fleck, which can, because of the presence of the pigment, absorb more light than the skin cells, and are more sensitive to the light. By such pigment-flecks, or eye-spots, the animal can detect, by their shadows, the passing near them of moving bodies, and thus be in some measure informed of the approach of enemies or of...
Página 127 - The head usually carries the eyes, a pair of feelers (antennae), and three pairs of mouth-parts which may be fashioned into a long, slender tube to be used in sucking, and frequently as a piercing organ ; or they may be constructed for cutting and biting. The thorax bears three pairs of legs and often one or two pairs of wings. The appendages of the abdomen are usually small and few in number, or even absent. 113. Internal anatomy. — The restless activity of insects is proverbial. Some appear to...
Página 357 - Others are dull earth-coloured, and hide in holes and under logs. All these come out only at night to feed, and they are all preyed upon by snakes and birds. In contrast with these obscurely...
Página 359 - 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...
Página 279 - 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 336 - ... regard to their mode of development and life are called facultat.ive. parasites. These latter may indeed be able to go through life -as free-living, nonparasitic animals, although, with opportunity, they live parasitically. In nearly all cases the body of a parasite is simpler in structure than the body of other animals which are closely related to the parasite — that is, animals that live parasitically have simpler bodies than animals that live free active lives, competing for food with the...
Página 378 - The male mosquitoes (Fig. 149) have many hundreds of these long, fine antennal hairs, and on the sounding of a tuning-fork these hairs have been observed to vibrate strongly. In the base of each antenna there is a most elaborate organ, composed of fine chitinous rods, and accompanying nerves and nerve cells whose function it is to take up and transmit through the auditory nerve to the brain the stimuli received from the external auditory hairs.
Página 321 - Andrena, which make little burrows in a clay bank, live in large colonies — that is, they make their nest burrows close together in the same clay bank, but each female makes her own burrow, lays her own eggs in it, furnishes it with food — a kind of paste of nectar and pollen — and takes no further care of her young. Nor has she at any time any special interest in her neighbors. But with the smaller mining bees, belonging to the genus Halictus...