Essentials of Biology Presented in Problems: By George William HunterAmerican book Company, 1911 - 448 páginas |
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Página 31
... cells may be so minute that in the case of the plant cells named bacteria , several million could be placed on the dot of this letter i . The forms of cells may be extremely varied in different tissues ; they may assume the form of ...
... cells may be so minute that in the case of the plant cells named bacteria , several million could be placed on the dot of this letter i . The forms of cells may be extremely varied in different tissues ; they may assume the form of ...
Página 35
... cell . When we see it , however , we can distinguish two nuclei in the protoplasm . Hence we know that at least two cells exist there . Growth of Pollen Grains . - Under A pollen grain highly magnified . certain conditions a pollen ...
... cell . When we see it , however , we can distinguish two nuclei in the protoplasm . Hence we know that at least two cells exist there . Growth of Pollen Grains . - Under A pollen grain highly magnified . certain conditions a pollen ...
Página 36
... cell which grows into the pollen tube is known as the sperm cell . ― Fertilization of the Flower . If we cut the pistil of a large flower ( as a lily ) ... cells , after coming together , unite to form a single cell 36 FLOWERS AND THEIR WORK.
... cell which grows into the pollen tube is known as the sperm cell . ― Fertilization of the Flower . If we cut the pistil of a large flower ( as a lily ) ... cells , after coming together , unite to form a single cell 36 FLOWERS AND THEIR WORK.
Página 37
... cell . This process is known as fertilization . This single cell formed by the union of the pollen tube cell or sperm and the egg cell is now called a fertilized egg . - Development of Ovule into Seed . The primary reason for the ...
... cell . This process is known as fertilization . This single cell formed by the union of the pollen tube cell or sperm and the egg cell is now called a fertilized egg . - Development of Ovule into Seed . The primary reason for the ...
Página 87
... cells , most of which are dead , loosely ar- ranged so as to form a cap over the growing tip . This is evidently an adaptation which protects the young and actively growing cells just under the root cap . In the body of the root the ...
... cells , most of which are dead , loosely ar- ranged so as to form a cap over the growing tip . This is evidently an adaptation which protects the young and actively growing cells just under the root cap . In the body of the root the ...
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Términos y frases comunes
adapted alcohol algæ American Book Company Appleton and Company bacteria bean bees beetle birds blood body BOOKS ELEMENTARY Sharpe Botany called carbon dioxide caused cavity cells cent chlorophyll color containing corn cotyledons covered crab crayfish crustaceans developed digestive disease eggs endosperm example fish flower fluid food material food tube forest frog fruit fungi germinate germs gills glands grain grape sugar green plants grow growth heat hypocotyl important insects intestine known Laboratory Manual large number larvæ layer leaf leaves living lungs Macmillan Company mouth muscles nerve nervous system nitrogen organs osmosis oxidation oxygen paramecium parasites pass peas plants and animals poison pollen Prob proteid protoplasm Protozoa REFERENCE BOOKS ELEMENTARY root hair seeds seen skeleton skin soil species sperm sponge spores starch stem stomata structure substances supply surface temperature tiny tion tissues trees typhoid walls wings worm xerophytes young plant
Pasajes populares
Página 405 - As we become permanent drunkards by so many separate drinks, so we become saints in the moral, and authorities and experts in the practical and scientific spheres, by so many separate acts and hours of work.
Página 405 - The hell to be endured hereafter, of which theology tells, is no worse than the hell we make for ourselves in this world by habitually fashioning our characters in the wrong way.
Página 405 - I won't count this time." Well ! he may not count it, and a kind Heaven may not count it ; but it is being counted none the less. Down among his nerve cells and fibers the molecules are counting it, registering and storing it up to be used against him when the next temptation comes.
Página 405 - Let no youth have any anxiety about the upshot of his education, whatever the line of it may be. If he keep faithfully busy each hour of the working day, he may safely leave the final result to itself. He can with perfect certainty count on waking up some fine morning to find himself one of the competent ones of his generation, in whatever pursuit he may have singled out..
Página 405 - Could the young but realize how soon they will become mere walking bundles of habits, they would give more heed to their conduct while in the plastic state. We are spinning our own fates, good or evil, and never to be undone. Every smallest stroke of virtue or of vice leaves its never so little scar. The drunken Rip Van Winkle, in Jefferson's play, excuses himself for every fresh dereliction by saying, 'I won't count this time!
Página 380 - One of the most common and pernicious of the popular errors relating to alcohol is the supposition that it somehow strengthens the heart. The full, bounding pulse, usually produced by the administration of an ounce or two of brandy, gives the impression of an increased vigor of heart action; but it is only necessary to determine the blood pressure by means of a Riva-Rocci instrument or Gaertner's tonometer, to discover that the blood pressure is not raised and may be lowered.
Página 427 - If one's use of diet and air is proper, the fatigue point will be much further off than otherwise. One should learn to relax when not in activity. The habit produces rest, even between exertions very close together, and enables one to continue to repeat those exertions for a much longer time than otherwise. The habit of lying down when tired is a good one. The same principles apply to mental rest. Avoid worry, anger, fear, excitement, hate, jealousy, grief, and all depressing or abnormal mental states....
Página 347 - In small doses these substances are oxidized in the body and yield a corresponding amount of energy, but their value from this standpoint is altogether unimportant compared with their action as stimulants. Alcohol also, when not taken in too large quantities, may be oxidized in the body, and furnish a not inconsiderable amount of energy. It is, however, a matter of controversy at present whether alcohol in small doses can be considered a true foodstuff, capable of serving as a direct source of energy,...
Página 414 - In like manner the influence of all drugs which affect the nervous system must be in the direction of disintegration. The healthy mind stands in clear and normal relations with Nature. It feels pain as pain. It feels action as pleasure. The drug which conceals pain or gives a false pleasure when pleasure does not exist forces a lie upon the nervous system.
Página 430 - If we count the value of each life lost at only $1,700 and reckon the average earning lost by illness at $700 per year for grown men, we find that the economic gain from mitigation of preventable disease in the United States would exceed $1,500,000,000 a year.