Life and Evolution: An Introduction to General BiologyHarcourt, Brace, 1926 - Всего страниц: 449 |
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Стр. 64
... inter- FIG . 28 - Parama- cium aurelia di- viding . The mac- ronucleus , m , and the two micronu- clei , nk , nk ' , are in division ; o , o ' , mouth . rupted by a form of sexual reproduction , or conjugation 64 GENERAL BIOLOGY.
... inter- FIG . 28 - Parama- cium aurelia di- viding . The mac- ronucleus , m , and the two micronu- clei , nk , nk ' , are in division ; o , o ' , mouth . rupted by a form of sexual reproduction , or conjugation 64 GENERAL BIOLOGY.
Стр. 65
An Introduction to General Biology Samuel Jackson Holmes. rupted by a form of sexual reproduction , or conjugation . Indi- viduals become attached by their oral surfaces and swim about in pairs . In the meantime , changes take place in ...
An Introduction to General Biology Samuel Jackson Holmes. rupted by a form of sexual reproduction , or conjugation . Indi- viduals become attached by their oral surfaces and swim about in pairs . In the meantime , changes take place in ...
Стр. 66
... sexual reproduction , is followed by a period of growth and encystment , in which the flagella disappear and the whole organism assumes a spherical form . Encystment also occurs without conjugation . In the encysted state the organism ...
... sexual reproduction , is followed by a period of growth and encystment , in which the flagella disappear and the whole organism assumes a spherical form . Encystment also occurs without conjugation . In the encysted state the organism ...
Стр. 168
... reproduction . In sexual reproduction there is a union of gametes , or sexual cells , which precedes , and is often necessary to initiate , the reproductive process . As we have already seen , sexual reproduction occurs in both unicellu ...
... reproduction . In sexual reproduction there is a union of gametes , or sexual cells , which precedes , and is often necessary to initiate , the reproductive process . As we have already seen , sexual reproduction occurs in both unicellu ...
Стр. 170
... sexual reproduction of the higher animals . The divisions of the micronuclei preparatory to conjugation suggest the ... fertilization . Whether the division of the micro- nuclei actually effects a reduction in the number of chromosomes ...
... sexual reproduction of the higher animals . The divisions of the micronuclei preparatory to conjugation suggest the ... fertilization . Whether the division of the micro- nuclei actually effects a reduction in the number of chromosomes ...
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algæ Amoeba ants appearance b₁ b2 B2 b₁ bacteria become birds blood body called carried causes cavity cell division centrosomes characters chemical chromosomes cœlom colony color commonly crustaceans cytoplasm Darwin digestive disease ectoderm eggs embryo epithelium evolution fact factors female fermentation fertilized fibers fluid forms function gametes gastrula germ cells germ plasm gill glands green hereditary heredity higher animals human Hydra hydroids individuals inheritance insects intestine kinds known large number larvæ later layer liver living lower Macmillan male mammals Mendelian micronucleus mitosis muscles nerve nest notochord nucleus occur organisms outer ovum pairs parasites parents parthenogenesis peculiar period plants and animals pollen primitive produced progeny proteins protoplasm queen regeneration region relation relatively reproduction result secretion sex cells sexual species sperm spores stage structure substance surface synapsis theory tion tissue usually ventral vertebrates vessels wall worms X chromosome young
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Стр. 353 - I look at the geological record as a history of the world imperfectly kept, and written in a changing dialect; of this history we possess the last volume alone, relating only to two or three countries. Of this volume, only here and there a short chapter has been preserved; and of each page, only here and there a few lines.
Стр. 395 - Given any species in any region, the nearest related species is not likely to be found in the same region nor in a remote region, but in a neighboring district separated from the first by a barrier of some sort.
Стр. 10 - Life is a series of definite and successive changes, both of structure and composition, which take place within an individual without destroying its identity.
Стр. 222 - ... mandibles have lost their teeth, and have become mere nippers, deadly weapons indeed, but useless except in war. They have lost the greater part of their instincts : their art, that is, the power of building ; their domestic habits, for they take no...
Стр. 411 - One half of the Jukes were and are feeble-minded, mentally incapable of responding normally to the expectations of society, brought up under faulty environmental conditions which they consider normal, satisfied with the fulfillment of natural passions and desires, and with no ambition or ideals in life.
Стр. 206 - Duvaucel saw a Hylobates washing the faces of her young ones in a stream. So intense is the grief of female monkeys for the loss of their young, that it invariably caused the death of certain kinds kept under confinement by Brehm in North Africa.
Стр. 229 - Yet although the ox has so little affection for, or individual interest in, his fellows, he cannot endure even a momentary severance from his herd. If he be separated from it by stratagem or force, he exhibits every sign of mental agony ; he strives with all his might to get back again, and when he succeeds, he plunges into its middle to bathe his whole body with the comfort of closest companionship.
Стр. 333 - Creator; but unless it be specified whether order in time or space, or both, or what else is meant by the plan of the Creator, it seems to me that nothing is thus added to our knowledge. Expressions such as that famous one by Linnaeus, which we often meet with in a more or less concealed form, namely, that the characters do not make the genus, but that the genus gives the characters, seem to imply that some deeper bond is included in our classifications than mere resemblance. I believe that this...
Стр. 194 - The bullfinch makes his advances in front of the female, and then puffs out his breast, so that many more of the crimson feathers are seen at once than otherwise would be the case. At the same time he twists and bows his black tail from side to side in a ludicrous manner. The male chaffinch also stands in front of the female, thus shewing his red breast and 'blue bell...
Стр. 92 - Divel has raised those Arsenical Fumes, which become Venomous Quivers full of Terrible Arrows, how easily can he shoot the deleterious Miasms into those Juices or Bowels of Men's Bodies, which will soon Enflame them with a Mortal Fire...