The Study of Animal LifeSribner, 1917 - 477 pages |
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Page x
... ovum -6 . The male - cell or spermatozoon - 7 . Maturation - 8 . Fer- tilisation pp . 298-312 CHAPTER XV DEVELOPMENT 1. Segmentation and after - 2 . Differentiation - 3 . Some generalisa- tions : ( a ) The ovum theory ; ( b ) the ...
... ovum -6 . The male - cell or spermatozoon - 7 . Maturation - 8 . Fer- tilisation pp . 298-312 CHAPTER XV DEVELOPMENT 1. Segmentation and after - 2 . Differentiation - 3 . Some generalisa- tions : ( a ) The ovum theory ; ( b ) the ...
Page 189
... ovum is to begin with a simple mass of matter , in part , at least , alive , and that by division after division the egg gives rise to a young animal . We are also well aware that in most cases the egg - cell , for cell it is , only ...
... ovum is to begin with a simple mass of matter , in part , at least , alive , and that by division after division the egg gives rise to a young animal . We are also well aware that in most cases the egg - cell , for cell it is , only ...
Page 190
... ovum and its daughter - cells . In those plants with which we are most familiar , the facts seem different , for we watch bean and oak growing from seeds which , instead of being simple units , are very complex structures . But the seed ...
... ovum and its daughter - cells . In those plants with which we are most familiar , the facts seem different , for we watch bean and oak growing from seeds which , instead of being simple units , are very complex structures . But the seed ...
Page 195
... ovum cohere to form a young animal . The gulf between the single - celled and many - celled animals is a deep one , but it has been bridged . Otherwise we should not exist . Traces of the bridge now remain in what are called " colonial ...
... ovum cohere to form a young animal . The gulf between the single - celled and many - celled animals is a deep one , but it has been bridged . Otherwise we should not exist . Traces of the bridge now remain in what are called " colonial ...
Page 198
... ovum which has been or FIG . OF 51. - A SINGLE CELL CILIATED EPITHELIUM ΤΟ IL- LUSTRATE A LITTLE OF THE COMPLEXITY THAT THERE MAY BE IN CELLS . ( After Schneider . ) At the roots of the cilia ( C ) there are basal corpuscles ( B ) , and ...
... ovum which has been or FIG . OF 51. - A SINGLE CELL CILIATED EPITHELIUM ΤΟ IL- LUSTRATE A LITTLE OF THE COMPLEXITY THAT THERE MAY BE IN CELLS . ( After Schneider . ) At the roots of the cilia ( C ) there are basal corpuscles ( B ) , and ...
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Common terms and phrases
activity adaptations adult amoeboid Amphibians ants ARTHUR THOMSON become bees begin behaviour Biology birds body brain buds called cells centrosome changes characteristic characters chromosomes cilia colony colour complex crab creatures crustaceans cuttlefish Darwin Echinoderms egg-cell eggs embryo environment evolution Evolution of Sex eyes fact female fertilised fishes flowers food-canal forms freshwater frog function germ-cells gills grow habit heredity higher animals hydroid illustration individual influence Infusorians inheritance insects instinctive kind lancelet larva larvæ life-history living matter London male mammals mates molluscs mouth muscles Natural History naturalists nervous system nest notochord nucleus nurture nutritive offspring organism ovum pairs parasitic parents physiological plants Prof Protozoa RAY LANKESTER reproductive reptiles result Rotifers sea-anemones shells simplest skin sometimes species spermatozoon spiders sponges starfish structure struggle for existence surface surroundings T. H. MORGAN theory tion tissues trans Vertebrates vols wings worms young Zoology
Popular passages
Page 323 - Tis but an hour ago since it was nine, And after one hour more 'twill be eleven ; And so, from hour to hour, we ripe and ripe, And then, from hour to hour, we rot and rot ; And thereby hangs a tale.
Page 196 - I believe a leaf of grass is no less than the journey-work of the stars, And the pismire is equally perfect, and a grain of sand, and the egg of the wren, And the tree-toad is a...
Page 159 - In no case may we interpret an action as the outcome of the exercise of a higher psychical faculty, if it can be interpreted as the outcome of the exercise of one which stands lower in the psychological scale.
Page 196 - And the pismire is equally perfect, and a grain of sand, and the egg of the wren, And the tree-toad is a chef-d'oeuvre for the highest, And the running blackberry would adorn the parlors of heaven, And the narrowest hinge in my hand puts to scorn all machinery, And the cow crunching with depressed head surpasses any statue, And a mouse is miracle enough to stagger sextillions of infidels.
Page 46 - Are God and Nature then at strife, That Nature lends such evil dreams So careful of the type she seems, So careless of the single life...
Page 284 - It scarcely breathes with its one lung (the other shrivelled and abortive) ; it is passive to the sun and shade, and is cold or hot like a stone ; yet " it can outclimb the monkey, outswim the fish, outleap the zebra, outwrestle the athlete, and crush the tiger.
Page 369 - germ-plasm,' and have assumed that it possesses a highly complex structure, conferring upon it the power of developing into a complex organism. I have attempted to explain heredity by supposing that in each ontogeny, a part of the specific germ-plasm contained in the parent egg-cell is not used up in the construction of the body of the offspring, but is reserved unchanged for the formation of the germ-cells of the following generation.
Page 417 - Fifthly, from their first rudiment, or primordium, to the termination of their lives, all animals undergo perpetual transformations, which are in part produced by their own exertions in consequence of their desires and aversions, of their pleasures and pains, or of irritations, or of associations; and many of these acquired forms or propensities are transmitted to their posterity.
Page 36 - I should premise that I use the term Struggle for Existence in a large and metaphorical sense, including dependence of one being on another, and including (which is more important) not only the life of the individual, but success in leaving progeny.
Page 417 - As air and water are supplied to animals in sufficient profusion, the three great objects of desire, which have changed the forms of many animals by their exertions to gratify them, are those of lust, hunger and security.