FOOTNOTES:[17]The second section contains references to the following treatises:C. V. Naegeli:Mechanisch-physiologische Theorie der Abstammungslehre(1884).Hertwig, Oscar:Lehrbuch der Entwicklungsgeschichte des Menschen und der Wirbelthiere; 4th edit.Sachs:Lectures on Plant Physiology; English edition, Clarendon Press.Voechting:Ueber die Theilbarkeit im Pflanzenreich und die Wirkung innerer und äusserer Kräfte auf Organbildung an Pflanzentheilen.Pflüger's Archiv., vol. xv., 1877.Ibid.:Ueber Organbildung im Pflanzenreich, 1, 2; Bonn, 1878, 1884.Goebel:Beiträge zur Morphologie und Physiologie des Blattes.Bot. Zeit., 1880.Pflüger:Die teleologische Mechanik der lebendigen Natur; Bonn, 1877.Maupas:Sur le déterminisme de la sexualité chez l'Hydatina senta.Comptes rendus des séances de l'Académie des Sciences; Paris, 1891.Weismann:Die Allmacht der Naturzüchtung. Eine Erwiderung an Herbert Spencer; Jena, 1893.Herbert Spencer:A Rejoinder to Professor Weismann.Contemporary Review, 1893.Ibid.:Die Unzulänglichkeit der 'Natürlichen Zuchtwahl.'Biol. Centralblatt, vol. xiv., No. 6.Emery:Die Entstehung und Ausbildung des Arbeiterstandes bei den Ameisen.Biol. Centralb., vol. xiv., No. 2, 1894.Haacke;Gestaltung and Vererbung(1894).[18]The assumption of doubling division does not involve the assumption that the germinal mass is unalterable. Although I do not regard the process of division as a mechanism for breaking up the idioplasm into dissimilar groups of determinants, I regard the idioplasm—and here I agree with Naegeli—as only relatively stable. In course of time external and internal forces may slowly alter it. On the one hand, the idioplasm of the reproductive cells in the course of generations may slowly alter, while, on the other hand, the idioplasm of cell groups in an organism may acquire a local character in correspondence with their different topographical and functional positions in the whole creature, and in relation to their place in the organic division of labour, just as in human communities individuals become altered by the lifelong exercise of some calling.Nor does the doctrine of doubling divisions conflict with those conclusions of pathology according to which, in the process of regeneration, cells and tissues give rise only to cells and tissues of their own order. For further details see my treatise,Ei und Samen-Bildung bei Nematoden, pp. 97-99. These slight suggestions are only to prevent misconceptions.
[17]The second section contains references to the following treatises:C. V. Naegeli:Mechanisch-physiologische Theorie der Abstammungslehre(1884).Hertwig, Oscar:Lehrbuch der Entwicklungsgeschichte des Menschen und der Wirbelthiere; 4th edit.Sachs:Lectures on Plant Physiology; English edition, Clarendon Press.Voechting:Ueber die Theilbarkeit im Pflanzenreich und die Wirkung innerer und äusserer Kräfte auf Organbildung an Pflanzentheilen.Pflüger's Archiv., vol. xv., 1877.Ibid.:Ueber Organbildung im Pflanzenreich, 1, 2; Bonn, 1878, 1884.Goebel:Beiträge zur Morphologie und Physiologie des Blattes.Bot. Zeit., 1880.Pflüger:Die teleologische Mechanik der lebendigen Natur; Bonn, 1877.Maupas:Sur le déterminisme de la sexualité chez l'Hydatina senta.Comptes rendus des séances de l'Académie des Sciences; Paris, 1891.Weismann:Die Allmacht der Naturzüchtung. Eine Erwiderung an Herbert Spencer; Jena, 1893.Herbert Spencer:A Rejoinder to Professor Weismann.Contemporary Review, 1893.Ibid.:Die Unzulänglichkeit der 'Natürlichen Zuchtwahl.'Biol. Centralblatt, vol. xiv., No. 6.Emery:Die Entstehung und Ausbildung des Arbeiterstandes bei den Ameisen.Biol. Centralb., vol. xiv., No. 2, 1894.Haacke;Gestaltung and Vererbung(1894).
[17]The second section contains references to the following treatises:
C. V. Naegeli:Mechanisch-physiologische Theorie der Abstammungslehre(1884).
Hertwig, Oscar:Lehrbuch der Entwicklungsgeschichte des Menschen und der Wirbelthiere; 4th edit.
Sachs:Lectures on Plant Physiology; English edition, Clarendon Press.
Voechting:Ueber die Theilbarkeit im Pflanzenreich und die Wirkung innerer und äusserer Kräfte auf Organbildung an Pflanzentheilen.Pflüger's Archiv., vol. xv., 1877.
Ibid.:Ueber Organbildung im Pflanzenreich, 1, 2; Bonn, 1878, 1884.
Goebel:Beiträge zur Morphologie und Physiologie des Blattes.Bot. Zeit., 1880.
Pflüger:Die teleologische Mechanik der lebendigen Natur; Bonn, 1877.
Maupas:Sur le déterminisme de la sexualité chez l'Hydatina senta.Comptes rendus des séances de l'Académie des Sciences; Paris, 1891.
Weismann:Die Allmacht der Naturzüchtung. Eine Erwiderung an Herbert Spencer; Jena, 1893.
Herbert Spencer:A Rejoinder to Professor Weismann.Contemporary Review, 1893.
Ibid.:Die Unzulänglichkeit der 'Natürlichen Zuchtwahl.'Biol. Centralblatt, vol. xiv., No. 6.
Emery:Die Entstehung und Ausbildung des Arbeiterstandes bei den Ameisen.Biol. Centralb., vol. xiv., No. 2, 1894.
Haacke;Gestaltung and Vererbung(1894).
[18]The assumption of doubling division does not involve the assumption that the germinal mass is unalterable. Although I do not regard the process of division as a mechanism for breaking up the idioplasm into dissimilar groups of determinants, I regard the idioplasm—and here I agree with Naegeli—as only relatively stable. In course of time external and internal forces may slowly alter it. On the one hand, the idioplasm of the reproductive cells in the course of generations may slowly alter, while, on the other hand, the idioplasm of cell groups in an organism may acquire a local character in correspondence with their different topographical and functional positions in the whole creature, and in relation to their place in the organic division of labour, just as in human communities individuals become altered by the lifelong exercise of some calling.Nor does the doctrine of doubling divisions conflict with those conclusions of pathology according to which, in the process of regeneration, cells and tissues give rise only to cells and tissues of their own order. For further details see my treatise,Ei und Samen-Bildung bei Nematoden, pp. 97-99. These slight suggestions are only to prevent misconceptions.
[18]The assumption of doubling division does not involve the assumption that the germinal mass is unalterable. Although I do not regard the process of division as a mechanism for breaking up the idioplasm into dissimilar groups of determinants, I regard the idioplasm—and here I agree with Naegeli—as only relatively stable. In course of time external and internal forces may slowly alter it. On the one hand, the idioplasm of the reproductive cells in the course of generations may slowly alter, while, on the other hand, the idioplasm of cell groups in an organism may acquire a local character in correspondence with their different topographical and functional positions in the whole creature, and in relation to their place in the organic division of labour, just as in human communities individuals become altered by the lifelong exercise of some calling.
Nor does the doctrine of doubling divisions conflict with those conclusions of pathology according to which, in the process of regeneration, cells and tissues give rise only to cells and tissues of their own order. For further details see my treatise,Ei und Samen-Bildung bei Nematoden, pp. 97-99. These slight suggestions are only to prevent misconceptions.
AAcineta, a group of protozoa, development of,41.Acquired characters, question of their inheritance,x.Amphioxus, a marine animal, representative of the primitive vertebrate stock, experiments on eggs of,61.Anabolism, the formation of more complex chemical bodies by the agency of protoplasm,86.Animal cells, characteristic mode of growth,111.Antennularia, Loeb's experiment,117.Ants, polymorphism in,125.Ascidians, tunicate animals,46.Atavism, the occurrence in an organism of a character abnormal in it, but normal in an ancestor,24.BBees, polymorphism in,125.Beetroot, grafting experiments,121.Begonia, reproduction from leaves,46.Beet, experiments on rats,73.Beresowsky, skin-grafting,75.Beyerinck, upon galls,51.Biophores. Each determinant, according to Weismann, is composed of a number of ultimate living pieces, the biophores, which are the active agents that direct the functions of a mature cell,ix,22.Blastosphere,an early stage in embryonic development; the embryo consists of a hollow sphere, the walls of which consist of a single layer of cells, and the cavity of which is called the segmentation cavity,xvii;explanation of formation,97,98.Blood, transfusion of,75.Blumenbach,nisus formativus,5;upon galls,50.Bone-grafting,73,74.Bonellia, sexual dimorphism in,122.Bryozoa, a group of minute animals which form encrustations on seaweeds and stones,46.Buds, origin of,28;reproduction and regeneration by,46.CCell, description of,31;characters possible in,88;differentiation of, in development,112;as units in morphology and physiology,113;Sachs on,114;Vöchting on,114,116.Cell theory, relation of, to heredity,31.Centrosome, an organ of cells most obvious during nuclear division,93.Cerianthus, experimental heteromorphoses,51.Chabry, destruction of segmentation sphere,62.Chromatin, a material found in the nucleus of cells, so called because it absorbs stains with avidity: germplasm and,viii,xiv;relation of, to specific character of cells,36,37.Chromosomes, definite, visible bodies, as which the chromatin of a dividing nucleus appears,xiv,93.Crystal, growth of, compared with organic growth,108.Cione, experimental heteromorphoses,52.Clavellina, reproduction from buds,46.Cleavage-planes, the planes separating the daughter-nuclei, or daughter-cells, in the early division of a fertilised egg-cell,xvii;relation between appearance of, and structure of eggs,95.Cœlenterata, a major division of multicellular animals, including such creatures as sea-anemones, corals, and jelly-fish,46.Continuity of the germplasm,26.Continuity of life, the doctrine opposed to spontaneous generation,2.Correlations,118,121.DDarwin, pangenesis,21.Determinants. Eachidof germplasm is supposed by Weismann to be composed of minor pieces, arranged in a complicated fashion that is the result of the past history of the species. For every part of the body, large or small, that may be different in different individuals or species, there is, at least, one determinant in theid. The determinants are so grouped in theidthat they are liberated and become active when the time comes for the development of that part of the body they control,viii,22;arguments against,82;relation to cells,87.Determinates, the smallest parts of an organism which vary independently, and which are supposed by Weismann to be represented in the germplasm by special pieces,23,25.Differentiating division, such a division of the nucleus as would result in daughter-nuclei unlike each other, and unlike the parent nucleus. The qualities of the parent nucleus are supposed to have been distributed between the daughter-nuclei,xi;absence of visible evidence for,xv,25;objections to occurrence of,34,78.Dimorphism, the appearance of the same species in two different forms, sexual dimorphism,122,124.Disharmonic union in grafting,70.Double monsters, as examples of heteromorphosis,63.Doubling division. When an amœba reproduces by simple division, the daughter-amœbæ are identical, and each is identical with the parent except in size; from one amœba two have been formed. A doubling division of the nucleus is such as would result in the formation of two nuclei alike in every respect,ix;visible evidence for,xv,24;in unicellular organisms,40;occurrence of, with differentiating division,78.Driesch, experiments on eggs,54;separation of segmentation spheres,60.EEchinoderms, a group of marine animals, of which the star-fish is the most familiar type, eggs of,54.Echinoidea, a group of echinoderms,61.Ectoderm, the tissue in an adult derived from the epiblast (which see),19.Egg, relation between structure and division of,94;specific character of,135.Emery, on polymorphism in ants,128.Endoderm, the tissue in an adult, derived from the hypoblast (which see),19.Enfoldment. See Evolution.Epiblast. In the development of all multicellular animals, the young embryo soon becomes divided into two sets of cells, the epiblast and hypoblast; where a gastrula is formed, the outer layer of cells is the epiblast, the inner layer the hypoblast,xviii.Epigenesis, the doctrine that the formation of a new individual is not the mere out-growing of particles hidden in the egg-cell, but the result of moulding external forces,xiii;Roux's definition of,7;Weismann's denial of,9;epigenetic explanation of stages in development,98;summary of Hertwig's acceptance of,136.Evolution. Originally the term was applied, not to the origin of existing forms of life from common ancestors, but to the doctrine that every living creature contained within it the whole series of its future descendants, and that the growth of a living creature was evolving of one of these enfolded miniatures,xiii,1,2,3;Roux's contrast of, with epigenesis,6;the new evolution,10;Hertwig's partial agreement with,135,136.Experiment, Weismann's caution against,10.FFertilisation, the union of the nuclear matter of a male cell with the nuclear matter of a female cell,xii,xiv.Foraminifera, a group of protozoa provided with shells,44.Forel, on eyes of ants,126.Frogs' eggs, Hertwig's experiments upon; development of, under compression,57-60.Funaria, reproduction from chopped pieces,46.GGalls,50.Gastrula, an early embryonic stage, most simply formed from the blastosphere by the invagination of one side of the wall, and consisting of a hollow sac, the walls of which are formed by two layers of cells,xviii,60;formation of,99.Gemmules. See Pangenesis.Germ, the youngest embryonic stage of an individual or organ,10.Germplasm, the substance supposed to be the material bearer of inherited qualities: Weismann's conception of,viii,20;identification of, with nuclear matter,21;account of Weissmann's theory,21-28.Germ-tracks, the hypothetical paths along which germplasm passes in an unaltered condition during development,27;objections to,81.Goebel, on plasticity of plants,120.Grafting,68,70;of Hydra,72;bone-grafting,73,74;skin-grafting,74,120,121.Grassi, polymorphism due to food,129.Gregarines, a group of parasitic protozoa, development of,41.HHaacke, declaration that Hertwig is evolutionary,135.Hæmoglobin, the red colouring matter of blood,75.Harmonic union in grafting,70.Heteromorphosis, explanation of,49;cases of,51,52;embryonic cases,54.His, presence of foci in the germ,13.Histogenous, producing microscopical characters,20.Histology, study of the microscopical characters of cells and tissues, differentiation,115.Hydatina, determination of sex,5;temperature,123.Hydra, regeneration in,47;grafting of,72.Hydromedusæ, a group of invertebrate animals, the typical members of which are branched colonies of polyps: Weismann's investigations on,viii,xii.Hypoblast. See Epiblast,xvi.Hypotrichous infusoria, a group of protozoa,41.IIds, hypothetical individual pieces, a number of which are supposed by Weismann to be present in the germplasm of every sexual cell, and each of which is supposed to contain the inherited material necessary for a complete new organism. It has been suggested that tiny beads seen within the chromosomes of a sexual cell are theids,viii,23,33.Idioblasts, Hertwig's name for hypothetical ultimate units of living matter,22,82;the ultimate units of living matter, according to De Vries,22.Idioplasm, as opposed to germplasm, which is the nuclear material of germ-cells; idioplasm is the nuclear material of tissue-cells,xi,38.Immortality, definition of,82;of germ-cells,ix;of unicellular organisms,17;of germ-cells,80.Individuality of cells,115.Invagination, the infolding of a layer of cells, as, for instance, in the transformation of a blastosphere into a gastrula,xvii.Isotropism, explained in footnote,33.KKaryokinesis, a complicated process of nuclear division,xiv.Katabolism, the formation of less complex chemical bodies by the agency of protoplasm,86.LLabile, unstable, constantly changing,38.Landois, experiments on transfusion of blood,75.Leibnitz, on immortality,82.Loeb, on heteromorphoses,49;on plasticity of animals,117.MMaupas, experiments on sex of rotifers,123.Melons, determination of sex by temperature,124.Mesoblast, in the development of the cœlomata, or three-layered multicellular animals; a third set of cells, the mesoblast, arises between the epiblast and hypoblast,xviii.Monsters, relation of, to division of egg-cell,63.Mosaic theory of Roux,56.Morphoplasm, the general protoplasm of a cell,35.Multicellular organisms, those in which the body is composed of many cells, specialized in different directions; cell-division in,43.Mus, experiments on grafting among mice and rats,74.Myxomycetes, sometimes called 'slime fungi,' a group of low organisms, consisting of creeping masses of protoplasm with many nuclei,33.NNaegeli, biological units,30;cross-fertilization and grafting compared,69;heredity,92;environment in development,104;on plasticity of plants,119;on specific characters of eggs,134.Nais, regeneration in,47.Notochord, formation of, from unusual cells,117.Nucleus, a specialized portion of the protoplasm of cells, different in chemical and physical properties (see Chromatin, Chromosomes), as the bearer of heredity,19.Nussbaum, views on origin of germ-cells,17.Nutrition, influence of, on development,2.OOllier, bone-grafting,73.Ontogeny, the development of an individual from the egg upwards,9.Osteoblasts, cells which are the active agents in bone-formation,73.Ovogenesis, the formation of egg-cells in the ovary,13.PPangenesis, Darwin's provisional hypothesis, that the sexual cells were composed of minute particles (gemmules), given off by all the cells of the body,21.Periosteum, a cellular sheath of bones,73.Physiological units, Herbert Spencer's name for hypothetical ultimate units of living matter,22.Pistachio, influence of temperature on,121.Plant-cells, mode of growth,110.Plasomes, Hertwig's name for theoretical units of protoplasm,32.Plasticity of plant tissues,117,119,120.Pluteus, a free-swimming larval stage in the development of echinoderms,54.Podophrya, reproduction of,41.Polymorphism, the appearance of the same species in several different forms in ants and social insects,125.Ponfick, on transfusion of blood,75.Preformation, identical with the original meaning of evolution, which see.Prothallus, the leaf-shaped green organism that grows from the spore of a fern and produces sexual organs,49.Pseudopodia, extensions of protoplasm beyond the general contour of the cell,41.RRadiolaria, a group of protozoa,44.Regeneration in plants and animals,45,47.Rhipsalis grafted on Opuntia,71.Roux, contrast between epigenesis and evolution,6;mosaic theory of,56.Rudiment, used here as a translation for the wordanlage, which means the first plotting-out or beginning of a living structure. Darwin showed that rudimentary organs in adult creatures were for the most part vestiges of organs that had lost their use. In this treatise 'rudiment' is applied to an organ or structure in its incipient condition, whether that incipient state be visible in a young embryo, or a hypothetical structure in the germplasm,6;latent rudiments,37.SSachs, on cells,114;on reaction and protoplasm,133.Salix purpurea, reproduction from galls,51.Schmitt, bone-grafting,74.Segmentation, the early division of a developing egg,xvii.Segmentation spheres, the cells resulting from the early divisions of a developing egg, separation of, by Wilson and Driesch,60.Segmentation cavity. See Blastosphere.Sex, determination of, by temperature,123,124.Sexual cells (spermatozoa in male, ova or egg-cells in female), the nucleated pieces of protoplasm which are the starting-point of the new generation in sexual reproduction, origin of,18.Soma, the body of a plant or animal as contrasted with the reproductive cells contained within it,45.Somatic cells, the cells of the soma; mortality of,17.Spencer, Herbert, controversy with Weismann on polymorphism in insects,125.Spermatogenesis, the formation of spermatozoa in the testis,13.Spontaneous generation,2.Stolon, a strand of tissue connecting the individuals of colonial animals,46.Strasburger, the value of the nucleus in heredity,13,18.TTermites, polymorphism in,125.Transfusion of blood,75.Transplantation of bone,73,74.Trembley, grafting of Hydra,72.Triton, an amphibian, experiments on the egg by constriction,64.Tubularia, experimental heteromorphoses,51.Tunicata, a group of marine animals clad with a leathery tunic,14.UUnicellular organisms, animals (protozoa) and plants (protophyta) with the simplest structure, each being a single cell: immortality of,17;division doubling in,40.Unit, definition of a biological,30.VVegetative affinity,66et seq.Vertebrates, regeneration of lost parts,47.Voechting, experiments on grafting,70;harmonic and disharmonic union,70;on cells,114,116;on plasticity of plants,117,119;on grafting,120.WWeismannand preformation,8-10;caution against experiment,12;sources of his theory,20,21;Hertwig's description of his theory,22;absence of proof for differentiating division,34;symmetry of egg and adult,55;immortality of germ-cells,17,80,82;germ-tracks,83;doubling division,102;controversy with Spencer,125.Willow, reproduction from slips,46.Wilson, separation of segmentation spheres of amphioxus egg,60.Wolff,Theoria Generationis,4.Wounds, healing of, in relation to idioplasm,xii.YYolk, nutritive material stored in an egg-cell,xvi.
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