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acters adult animals appear breed centrosome changes char chemical chro chromatin chromo chromosomal vesicles cleavage cells color color blindness combinations contrasting characters crossed cytoplasm daughter determined differential cause Drosophila Drosophila melanogaster ectoderm egg and sperm embryo endoderm environment environmental evidence evolution experience extrinsic fact factors of development female fertilized egg formed functions Galton gametes gastrula genes genotypes germ cells germinal germplasm give rise heredity human hybrid individual inheritance kinds known male maturation Mendel Mendelian Mendelian inheritance ment mind mitosis modified mutations normal nucleus number of chromosomes offspring oosperm organism pairs Paramecium parents peas peculiarities phenomena physiological plants polar polar bodies poles possible present probably produced protoplasm pure dominants pure recessive race ratio reflexes responses result seeds segregation sex cells showing shown species sperm spermatozoa spindle stage stimuli structures substances tion types usually variations wrinkled X chromosomes yellow zygote
Page 71 - Great wits are sure to madness near allied; And thin partitions do their bounds divide: Else why should he, with wealth and honour blest, Refuse his age the needful hours of rest?
Page 210 - An organic being is a microcosm — a little universe, formed of a host of self-propagating organisms, inconceivably minute and numerous as the stars in heaven.
Page 30 - In all cases development begins with the fertilized egg which contains none of the structures of the developed animal, though it may exhibit the polarity and symmetry of the adult and may also contain specific kinds of protoplasm which will give rise to specific tissues or organs of the adult. From this egg cell arise by division many cells which differ from one another more and more as development proceeds, until finally the adult animal results. A specific type of development is due to a specific...
Page 199 - ... at the time of fertilization the hereditary potencies of the two germ cells are not equal, all the early stages of development, including the polarity, symmetry, type of cleavage, and the pattern, or relative positions and proportions of future organs, being foreshadowed in the cytoplasm of the egg cell, while only the differentiations of later development are influenced by the sperm. In short the egg cytoplasm fixes the general type of development and the sperm and egg nuclei supply only the...
Page 214 - ... as testifying that the power of judging aright and of distinguishing Truth from Error, which is properly what is called Good Sense or Reason, is by nature equal in all men; and that the diversity of our opinions, consequently, does not arise from some being endowed with a larger share of Reason than others, but solely from this, that we conduct our thoughts along different ways, and do not fix our attention on the same objects.
Page 296 - We greatly want a brief word to express the science of improving stock, which is by no means confined to questions of judicious mating, but which, especially in the case of man, takes cognisance of all influences that tend in however remote a degree to give to the more suitable races or strains of blood a better chance of prevailing speedily over the less suitable than they otherwise would have had.
Page 125 - Thus the problem which faces the student of heredity and development has been cut in two ; he no longer inquires how the body produces the germ cells, for this does not happen, but merely how the latter produce the body and other germ cells. The germ is the undeveloped organism which forms the bond between successive generations; the person is the developed organism which arises from the germ under the influence of environmental conditions. The person develops and dies in each generation; the germ...
Page 196 - A friend, a clergyman, who has read many novels tells me that he has been struck by the frequency with which novelists describe such scenes with much luxury of detail; his list includes novels by well-known religious writers of both sexes. In some of these cases there is reason to believe that the writers felt this sexual association of whipping. It is natural that an interest in whipping should be developed very early in childhood, and, indeed, it enters very frequently into the games of young children,...
Page 132 - Parents do not transmit their characters to their offspring, but their germ cells in the course of long development give rise to adult characters similar to those of the parents. The thing which persists more or less completely from generation to generation is the organization of the germ cells which differentiate in similar ways in successive generations if the extrinsic factors of development remain similar.