GLOSSARY
Abiogenesis: The discredited hypothesis that life may originate spontaneously in lifeless matter,i.e., apart from the influence of living matter.Adaptation: (1) The reciprocal aptitude of organism and environment for each other; (2) a structure, modification of structure, or behavioristic response enabling the organism to solve a special problem imposed by the environment; (3) the process by which the organism’s adjustment to the environment is brought about.Allelomorphs: Genes located opposite each other on homologous chromosomes and representing contrasting characters; they are separated during meiosis according to the Mendelian law of segregation,e.g.the genes for red and white in Four o’clocks which when united give rise to pink, and when segregated, to red and white flowers respectively, are allelomorphs of each other.Alluvial: Pertaining to the Alluvium, which consists of fresh-water deposits of the Pleistocene and Recent series, to be distinguished from the Diluvium which consists of older Pleistocene formations.Amino-acids: The chemical building-stones of the proteins—organic acids containing one or more amino-groups (—NH2) in place of hydrogen,e.g., amino-acetic acid, CH2·NH2·COOH.Amnion: A membranous bag which encloses the embryo in higher vertebrates. The lower vertebrates, namely, fishes and amphibia, have no amnion and are termed “anamniotic.” The reptiles, birds, and mammals which possess it are termed amniotic vertebrates.Amphioxus: The most simply organized animal having a dorsal notochord. It is classified among the Acrania incontradistinction to the craniate Chordates which make up the bulk of the vertebrates.Angiosperms: The higher plants, which have their seeds enclosed in seed-vessels.Anthropoid Apes: Apes of the familySimiidæ, which approach man most closely in their organization, namely, the chimpanzee, the gorilla, the gibbon, and orang-utan.Antibody: Chemical substances produced in the blood in reaction to the injection of antigens or toxic substances and capable of counteracting or neutralizing said substance. Such antibodies are specific for determinate antigens.Antigen: Any substance that causes the production of special antibodies in the blood of susceptible animals, after one or several injections.Arthropods: The phylum of exoskeletal invertebrates comprising crustaceans, arachnida, insects, etc.Atavism: The resemblance to an ancestor more distant than the parents.Automatism: A spontaneous action, not in response to recognizable stimuli.Basichromatin: That portion of a cell’s nuclear network which contains nuclein and is deeply stained by basic dyes.Biparental: Derived from two progenitors,i.e., a father and mother.Brachiopods: Invertebrate animals bearing a superficial resemblance to bivalve molluscs, but belonging to a totally different group—lamp shells.Cambrian: The “oldest” system of the Palæozoic group of fossiliferous rocks.Carbohydrates: The sugars, starches, etc.,—polyhydric alcohols with aldehydic or ketonic groups, and acetals of same, etc.Catalyst: A substance which accelerates a chemical reaction without permanently participating in it, being left over unchanged at the end of the process.Centriole: The centrioles or central bodies are the foci ofmitotic division in animal cells, as well as the source of the kinetic elements developed by such cells. They are minute bodies usually located within a larger sphere known as the centrosome or centrosphere. They do not occur in the cells of the higher plants.Cephalopods: A class of molluscs in which the foot is developed into a headlike structure with eyes and a circle of arms,e.g., the octopus, the cuttlefish, the squid, and the nautilus.Ceratites: A genus of extinct cephalopods having a coiled shell and crooked sutures.Character: An external feature or sensible property of an organism. It is the joint product of germinal factors (genes) and environmental influences.Chlorophyll: The green pigment formed in the chloroplasts (green plastids) of plant cells. It is a diester of phytyl and methyl alcohols with the tribasic acid, chlorophyllin, one of whose carboxyls is esterified with methyl alcohol, a second with phytol, while the third is otherwise engaged. Chlorophyllin is a tribasic acid consisting of the chlorophyllic chromogen group (containing magnesium) joined to three carboxyl groups.Chondriosomes: Cytoplasmic granules rodlike, threadlike, or spherical in form, which often appear to divide on the mitotic spindle, and are therefore credited with the power of independent growth and division. The chondriosomes of embryonic tissues are thought to be the original sources of the plastids, the fibrillæ, and certain metaplastic granules.Chordates: The phylum of animals whose primary axial skeleton consists temporarily or permanently of a notochord.Chromatin: Same as basichromatin.Chromosomes: The short threads or rodlike bodies into which the basichromatin of the cell-nucleus is aggregated during mitosis—each chromosome is segmented into granules called chromomeres—in its submicroscopic structure it consists of chain or linear series of genes (hereditary factors) representing characters linked together inheredity, each single chromosome being termed, on this account, a “linkage-group” by geneticists.Ciliate: A protozoan whose motor-apparatus consists of cilia,i. e., hairlike protoplasmic projections capable of rapid and coördinated vibratile movement.Cloaca: A common passageway through which the intestine, kidneys, and sex organs discharge their products,—it occurs in certain fishes, in amphibia, reptiles, and birds, and in a few mammals.Coccyx: Lower extremity of the vertebral column in man.Colloids: Insoluble gumlike substances, which will not diffuse through organic membranes.Commensalism: The harmonious cohabitation of two organisms belonging to different species, where the relation is not necessarily beneficial nor necessarily harmful to either.Crossover: The exchange or reciprocal transfer of whole blocks of genes from one homologous chromosome to the other, which sometimes occurs in synapsis, probably at the strepsinema-stage.Crystalloids: Soluble substances, which usually form crystals and readily diffuse through organic membranes.Cyst: A protective envelope formed around an organism during period of rest.Cytode: The non-nucleated cell hypothecated by Haeckel.Cyptoplasm: The cell-body or extranuclear protoplasm of a cell.Endomixis: A process of nuclear reorganization among the protozoa, which does not require the coöperation of two cells as in conjugation (amphimixis).Endoskeleton: An internal living skeleton providing support and protection (as well as organs of movement, in the bone-levers to which the muscles are attached)—it is characteristic of the vertebrates.Enzymes: Organic catalysts,i. e., complex chemical substances formed by organisms and serving to accelerate chemical processes taking place in said organisms,e. g.,the digestive enzymes, which accelerate the hydrolysis of starches, fats, and proteins.Epigenesis: Development of the embryo by differentiation of previously undifferentiated protoplasm.Fats: Esters of the higher fatty or organic acids (such as stearic, palmitic, and oleic) esterified with the trihydric alcohol glycerine (glycerol).Gamete: A reproductive cell specialized for syngamy,i.e., for union with a complementary germ cell, their union giving rise to a synthetic cell known as a zygote.Ganglion: An aggregate of nerve-cells consisting mainly of neural cell-bodies together with supporting cells.Ganoids: Fishes covered with enameled bony scales, and now, for the most part, extinct.Gene: A factor or infinitesimal element in a nuclear thread or chromosome, the latter being a linear aggregate of such factors, each having definite specificity and manifesting itself in the external character which develops from it.Genotype: The total assemblage of germinal factors transmitted by a given species of organism, that is, the complete complex of genes synthesized in the zygote and perpetuated by equation-divisions in the somatic cells. Hence the basic germinal or hereditary constitution of an organism or group of organisms.Germ Cells: Cells specialized for reproduction as contrasted with other vital functions,e.g., spores and gametes.Germ-plasm: The material basis of inheritance.Glacial Epoch: After the close of the Tertiary period, Europe and North America are said to have been covered with vast ice sheets known as continental glaciers (the result of great climatic changes in the Northern hemisphere). As the weather varied these ice sheets advanced and retreated, the retreats corresponding to the so-called Interglacial intervals. Four Glacial and three Interglacial stages are distinguished, and it was during the Second and Third of these Interglacial stages that Palæolithic Man is alleged to have entered Europe.Golgi Bodies: A cytoplasmic apparatus consisting, in its localized form, of a network, and, in its dispersed form, of scattered granules. It appears to divide on the mitotic spindle, and seems to have some important function connected with secretion.Habitat: The locality in which a given animal or plant normally lives.Hallux: The great toe, opposable in the ape, but not in man.Heredity: “The appearance in offspring of characters whose differential causes are in the germ cells” (Conklin).Heterozygous: Hybrid,—the condition in which the chromosomal genes paired by syngamy in the zygote are unlike.Homologous Chromosomes: Corresponding chromosomes of the same synaptic pair, being of paternal and maternal origin respectively.Homozygous: Pure,—the condition in which the chromosomal genes paired in the zygote by syngamy are alike.Hormone: An internal secretion elaborated in the endocrine or ductless glands and diffused in the blood stream for the purpose of influencing the activities or metabolism of parts of the organism at a distance from the source of the hormone,e. g., secretin, gastrin, adrenalin, etc.Hydrotheca: The cuplike extension of the perisarc (skeletal sheath) surrounding the hypostome (oral cone) and tentacles of certain polyps.Hyloblatic: Resembling the gibbon.Lemurs: Four-handed animals allied to the Insectivora, with curved nostrils and a claw instead of a nail on the first finger of the rear hands.Lethals: A genetical term for hereditary factors (genes) which cause the death of the gametes or the zygotes that contain them. In the case of zygotes, death results from the homozygous, but not from the heterzygous, condition.Linin: Same as oxychromatin.Litopterna: A suborder of extinct ungulate mammals from the Miocene and Pliocene of South America resembling horses or llamas.Mammals: Vertebrate animals which suckle their young after birth.Meiosis: The process whereby the chromosomes of synaptic pairs (in the primary oöcyte or spermatocyte) are separated in such a way that the resulting gametes (eggs, or sperms) receive a haploid (halved) number of unpaired chromosomes, instead of the diploid (double) number of paired chromosomes characteristic of the zygote and the somatic cells of the species.Metista: Animals and plants normally multicellular and having their cells differentiated into at least two distinct layers or tissues—the Metazoans and Metaphytes.Mitosis: Typical cell-division, whose mechanism consists of the spindle-fibers, and whose scope is to secure an exactly equal partition of the single components of the nucleus of the dividing cell between the two resultant daughter-cells.Monism: A system of thought which holds that there is but one substance, either mind (idealistic subjectivism), or matter (objectivistic materialism),—or else a substance that is neither mind nor matter, but is the substantial ground of both. Idealistic monism regards mind as the sole reality and matter as its product. Materialistic monism regards matter as the sole reality and mind as its product.Neolithic: Pertaining to the Young-Stone Age, that is, to prehistoric man of Post-glacial time. The implements of the latter are of polished stone. The Young-Stone Age is said to have begun about 7,000 yearsB.C., and to have ended with the Copper Culture about 2,000B.C.The Bronze Age, which followed it, belongs to history.Neurone: The nerve-cell with all its processes, consisting, therefore, of the nucleated cell-body, the axone or discharging fiber, and the dentrites or receiving fibers.Oölites: An English term for the Jurassic, or middle system of the Mesozoic group of fossiliferous rocks.Ontogeny: The embryological development of the individual.Opposable: A term applied to the thumb or great toe when they are capable of being placed with their tips opposite to those of the other digits.Organelle: Literally, a “miniature organ,”i.e., one of the living components of a cell as distinguished from the metaplastic or non-living inclusions.Oxychromatin: That portion of the nuclear network which stains with acidic dyes, the finer nuclear reticulum in which the coarser strands of basichromatin appear to be suspended.Palæolithic: Belonging to the Old-Stone Age, which corresponds to the latter half of the Glacial or Pleistocene epoch. It is alleged to be the second period of prehistoric man (following the Eolithic) and is characterized by implements of unpolished stone shaped from flint by the chipping off of flakes of the latter substance.Palæontology: The science of fossil organisms.Palæozoic: A term applied to the second group of fossiliferous rocks, following the earliest, or Proterozoic, group, and preceding the Mesozoic group. It comprises the Cambrian, Ordovician, Devonian, Silurian, and Carboniferous systems, and its sediments are the first that contain well-preserved fossils.Parasitism: A condition in which one organism (the parasite) residing in, or upon, another species of organism (the host) lives at its expense, the relation being detrimental to the latter.Parthenogenesis: The production of offspring from unfertilized eggs.Phenotype: The sum-total of external characters by whose enumeration an organism is described—the somatic or expressed characters of an organism (or group of organisms) as distinguished from those that are merely potential in the germ cells.Phylogeny: Developmental history of the race, the hypothetical evolutionary history of the race, in contradistinction to the embryological development of the individual (ontogeny).Phylum: A term used in classification to denote any primary group of the plant or animal kingdom.Plantigrade: Walking on the whole sole of the foot, like bears.Plastids: Permanent organelles or living components of the cellular cytoplasm,e.g., chloroplasts, leucoplasts, etc.Pleistocene: The lower series of the Quaternary system of fossiliferous rocks. It corresponds to the so-called Glacial epoch, and extends from the close of the Tertiary period (system) to the dawn of the Recent or Historical epoch.Polar Cell: A synonym for polar body, or policyte. The polar bodies are minute abortive cells given off by the egg undergoing meiosis. Into them are shunted the chromosomes which the egg discards in its process of nuclear reduction (maturation).Præformation: Theory that the egg contains a complete miniature of the organism into which it develops.Prehension: Grasping, catching hold.Progression: Advancing movement, locomotion.Pro-simiæ: The lemurs as distinguished from genuine apes (Simiæ).Protista: Animals or plants which are normally unicellular and which when multicellular show no differentiation into tissues—the Protozoans and Protophytes.Protoplasm: Living matter.Receptor: An organ specialized to receive stimuli,e.g., a sense-organ.Sedimentary: A term applied to rocks which originated as sediments deposited under water.Serum: Watery portion of the blood, the plasma.Somatic Cells: Vegetative cells not especially set aside by the organism for reproductive purposes,e.g., tissue-cells.Somite: One of the uniform segments of the longitudinal series into which a metameric organism (such as an earthworm) is partitioned.Spermatist: An old term applied to one who held that the animal embryo was produced entirely by the male parent.Spore: A single cell, incapable of syngamy, but capable of giving rise to a new individual without the sexual process.Symbiosis: The obligatory association of two organisms of different species for mutual benefit.Synapsis: Union in pairs of corresponding (homologous) chromosomes of opposite parental origin as a preliminary to their separation in meiosis.Systematist: An expert in classification (systematics),i. e., a taxonomist.Taxonomy: The science of classification.Tertiary Period: A geological time-division corresponding to the rock-system that comprises the greater part of the Cenozoic group. It is made up of four series, namely, the Eocene, Oligocene, Miocene, and Pliocene. Its close marks the beginning of the Glacial or Pleistocene epoch.Tissue: A layer of uniform cells specialized for the same function.Tissue Cell: One of the somatic cells of which a tissue is composed.Troglodytic: Resembling the chimpanzee and the gorilla.Woods Hole: The seat of the Marine Biological Laboratory. It is a watering-place on the New England coast opposite Martha’s Vineyard.Zygote: The synthetic cell formed by the union of two gametes and giving rise by division either to a new multicellular organism, or to a rejuvenated cycle of unicellular forms.
Abiogenesis: The discredited hypothesis that life may originate spontaneously in lifeless matter,i.e., apart from the influence of living matter.
Adaptation: (1) The reciprocal aptitude of organism and environment for each other; (2) a structure, modification of structure, or behavioristic response enabling the organism to solve a special problem imposed by the environment; (3) the process by which the organism’s adjustment to the environment is brought about.
Allelomorphs: Genes located opposite each other on homologous chromosomes and representing contrasting characters; they are separated during meiosis according to the Mendelian law of segregation,e.g.the genes for red and white in Four o’clocks which when united give rise to pink, and when segregated, to red and white flowers respectively, are allelomorphs of each other.
Alluvial: Pertaining to the Alluvium, which consists of fresh-water deposits of the Pleistocene and Recent series, to be distinguished from the Diluvium which consists of older Pleistocene formations.
Amino-acids: The chemical building-stones of the proteins—organic acids containing one or more amino-groups (—NH2) in place of hydrogen,e.g., amino-acetic acid, CH2·NH2·COOH.
Amnion: A membranous bag which encloses the embryo in higher vertebrates. The lower vertebrates, namely, fishes and amphibia, have no amnion and are termed “anamniotic.” The reptiles, birds, and mammals which possess it are termed amniotic vertebrates.
Amphioxus: The most simply organized animal having a dorsal notochord. It is classified among the Acrania incontradistinction to the craniate Chordates which make up the bulk of the vertebrates.
Angiosperms: The higher plants, which have their seeds enclosed in seed-vessels.
Anthropoid Apes: Apes of the familySimiidæ, which approach man most closely in their organization, namely, the chimpanzee, the gorilla, the gibbon, and orang-utan.
Antibody: Chemical substances produced in the blood in reaction to the injection of antigens or toxic substances and capable of counteracting or neutralizing said substance. Such antibodies are specific for determinate antigens.
Antigen: Any substance that causes the production of special antibodies in the blood of susceptible animals, after one or several injections.
Arthropods: The phylum of exoskeletal invertebrates comprising crustaceans, arachnida, insects, etc.
Atavism: The resemblance to an ancestor more distant than the parents.
Automatism: A spontaneous action, not in response to recognizable stimuli.
Basichromatin: That portion of a cell’s nuclear network which contains nuclein and is deeply stained by basic dyes.
Biparental: Derived from two progenitors,i.e., a father and mother.
Brachiopods: Invertebrate animals bearing a superficial resemblance to bivalve molluscs, but belonging to a totally different group—lamp shells.
Cambrian: The “oldest” system of the Palæozoic group of fossiliferous rocks.
Carbohydrates: The sugars, starches, etc.,—polyhydric alcohols with aldehydic or ketonic groups, and acetals of same, etc.
Catalyst: A substance which accelerates a chemical reaction without permanently participating in it, being left over unchanged at the end of the process.
Centriole: The centrioles or central bodies are the foci ofmitotic division in animal cells, as well as the source of the kinetic elements developed by such cells. They are minute bodies usually located within a larger sphere known as the centrosome or centrosphere. They do not occur in the cells of the higher plants.
Cephalopods: A class of molluscs in which the foot is developed into a headlike structure with eyes and a circle of arms,e.g., the octopus, the cuttlefish, the squid, and the nautilus.
Ceratites: A genus of extinct cephalopods having a coiled shell and crooked sutures.
Character: An external feature or sensible property of an organism. It is the joint product of germinal factors (genes) and environmental influences.
Chlorophyll: The green pigment formed in the chloroplasts (green plastids) of plant cells. It is a diester of phytyl and methyl alcohols with the tribasic acid, chlorophyllin, one of whose carboxyls is esterified with methyl alcohol, a second with phytol, while the third is otherwise engaged. Chlorophyllin is a tribasic acid consisting of the chlorophyllic chromogen group (containing magnesium) joined to three carboxyl groups.
Chondriosomes: Cytoplasmic granules rodlike, threadlike, or spherical in form, which often appear to divide on the mitotic spindle, and are therefore credited with the power of independent growth and division. The chondriosomes of embryonic tissues are thought to be the original sources of the plastids, the fibrillæ, and certain metaplastic granules.
Chordates: The phylum of animals whose primary axial skeleton consists temporarily or permanently of a notochord.
Chromatin: Same as basichromatin.
Chromosomes: The short threads or rodlike bodies into which the basichromatin of the cell-nucleus is aggregated during mitosis—each chromosome is segmented into granules called chromomeres—in its submicroscopic structure it consists of chain or linear series of genes (hereditary factors) representing characters linked together inheredity, each single chromosome being termed, on this account, a “linkage-group” by geneticists.
Ciliate: A protozoan whose motor-apparatus consists of cilia,i. e., hairlike protoplasmic projections capable of rapid and coördinated vibratile movement.
Cloaca: A common passageway through which the intestine, kidneys, and sex organs discharge their products,—it occurs in certain fishes, in amphibia, reptiles, and birds, and in a few mammals.
Coccyx: Lower extremity of the vertebral column in man.
Colloids: Insoluble gumlike substances, which will not diffuse through organic membranes.
Commensalism: The harmonious cohabitation of two organisms belonging to different species, where the relation is not necessarily beneficial nor necessarily harmful to either.
Crossover: The exchange or reciprocal transfer of whole blocks of genes from one homologous chromosome to the other, which sometimes occurs in synapsis, probably at the strepsinema-stage.
Crystalloids: Soluble substances, which usually form crystals and readily diffuse through organic membranes.
Cyst: A protective envelope formed around an organism during period of rest.
Cytode: The non-nucleated cell hypothecated by Haeckel.
Cyptoplasm: The cell-body or extranuclear protoplasm of a cell.
Endomixis: A process of nuclear reorganization among the protozoa, which does not require the coöperation of two cells as in conjugation (amphimixis).
Endoskeleton: An internal living skeleton providing support and protection (as well as organs of movement, in the bone-levers to which the muscles are attached)—it is characteristic of the vertebrates.
Enzymes: Organic catalysts,i. e., complex chemical substances formed by organisms and serving to accelerate chemical processes taking place in said organisms,e. g.,the digestive enzymes, which accelerate the hydrolysis of starches, fats, and proteins.
Epigenesis: Development of the embryo by differentiation of previously undifferentiated protoplasm.
Fats: Esters of the higher fatty or organic acids (such as stearic, palmitic, and oleic) esterified with the trihydric alcohol glycerine (glycerol).
Gamete: A reproductive cell specialized for syngamy,i.e., for union with a complementary germ cell, their union giving rise to a synthetic cell known as a zygote.
Ganglion: An aggregate of nerve-cells consisting mainly of neural cell-bodies together with supporting cells.
Ganoids: Fishes covered with enameled bony scales, and now, for the most part, extinct.
Gene: A factor or infinitesimal element in a nuclear thread or chromosome, the latter being a linear aggregate of such factors, each having definite specificity and manifesting itself in the external character which develops from it.
Genotype: The total assemblage of germinal factors transmitted by a given species of organism, that is, the complete complex of genes synthesized in the zygote and perpetuated by equation-divisions in the somatic cells. Hence the basic germinal or hereditary constitution of an organism or group of organisms.
Germ Cells: Cells specialized for reproduction as contrasted with other vital functions,e.g., spores and gametes.
Germ-plasm: The material basis of inheritance.
Glacial Epoch: After the close of the Tertiary period, Europe and North America are said to have been covered with vast ice sheets known as continental glaciers (the result of great climatic changes in the Northern hemisphere). As the weather varied these ice sheets advanced and retreated, the retreats corresponding to the so-called Interglacial intervals. Four Glacial and three Interglacial stages are distinguished, and it was during the Second and Third of these Interglacial stages that Palæolithic Man is alleged to have entered Europe.
Golgi Bodies: A cytoplasmic apparatus consisting, in its localized form, of a network, and, in its dispersed form, of scattered granules. It appears to divide on the mitotic spindle, and seems to have some important function connected with secretion.
Habitat: The locality in which a given animal or plant normally lives.
Hallux: The great toe, opposable in the ape, but not in man.
Heredity: “The appearance in offspring of characters whose differential causes are in the germ cells” (Conklin).
Heterozygous: Hybrid,—the condition in which the chromosomal genes paired by syngamy in the zygote are unlike.
Homologous Chromosomes: Corresponding chromosomes of the same synaptic pair, being of paternal and maternal origin respectively.
Homozygous: Pure,—the condition in which the chromosomal genes paired in the zygote by syngamy are alike.
Hormone: An internal secretion elaborated in the endocrine or ductless glands and diffused in the blood stream for the purpose of influencing the activities or metabolism of parts of the organism at a distance from the source of the hormone,e. g., secretin, gastrin, adrenalin, etc.
Hydrotheca: The cuplike extension of the perisarc (skeletal sheath) surrounding the hypostome (oral cone) and tentacles of certain polyps.
Hyloblatic: Resembling the gibbon.
Lemurs: Four-handed animals allied to the Insectivora, with curved nostrils and a claw instead of a nail on the first finger of the rear hands.
Lethals: A genetical term for hereditary factors (genes) which cause the death of the gametes or the zygotes that contain them. In the case of zygotes, death results from the homozygous, but not from the heterzygous, condition.
Linin: Same as oxychromatin.
Litopterna: A suborder of extinct ungulate mammals from the Miocene and Pliocene of South America resembling horses or llamas.
Mammals: Vertebrate animals which suckle their young after birth.
Meiosis: The process whereby the chromosomes of synaptic pairs (in the primary oöcyte or spermatocyte) are separated in such a way that the resulting gametes (eggs, or sperms) receive a haploid (halved) number of unpaired chromosomes, instead of the diploid (double) number of paired chromosomes characteristic of the zygote and the somatic cells of the species.
Metista: Animals and plants normally multicellular and having their cells differentiated into at least two distinct layers or tissues—the Metazoans and Metaphytes.
Mitosis: Typical cell-division, whose mechanism consists of the spindle-fibers, and whose scope is to secure an exactly equal partition of the single components of the nucleus of the dividing cell between the two resultant daughter-cells.
Monism: A system of thought which holds that there is but one substance, either mind (idealistic subjectivism), or matter (objectivistic materialism),—or else a substance that is neither mind nor matter, but is the substantial ground of both. Idealistic monism regards mind as the sole reality and matter as its product. Materialistic monism regards matter as the sole reality and mind as its product.
Neolithic: Pertaining to the Young-Stone Age, that is, to prehistoric man of Post-glacial time. The implements of the latter are of polished stone. The Young-Stone Age is said to have begun about 7,000 yearsB.C., and to have ended with the Copper Culture about 2,000B.C.The Bronze Age, which followed it, belongs to history.
Neurone: The nerve-cell with all its processes, consisting, therefore, of the nucleated cell-body, the axone or discharging fiber, and the dentrites or receiving fibers.
Oölites: An English term for the Jurassic, or middle system of the Mesozoic group of fossiliferous rocks.
Ontogeny: The embryological development of the individual.
Opposable: A term applied to the thumb or great toe when they are capable of being placed with their tips opposite to those of the other digits.
Organelle: Literally, a “miniature organ,”i.e., one of the living components of a cell as distinguished from the metaplastic or non-living inclusions.
Oxychromatin: That portion of the nuclear network which stains with acidic dyes, the finer nuclear reticulum in which the coarser strands of basichromatin appear to be suspended.
Palæolithic: Belonging to the Old-Stone Age, which corresponds to the latter half of the Glacial or Pleistocene epoch. It is alleged to be the second period of prehistoric man (following the Eolithic) and is characterized by implements of unpolished stone shaped from flint by the chipping off of flakes of the latter substance.
Palæontology: The science of fossil organisms.
Palæozoic: A term applied to the second group of fossiliferous rocks, following the earliest, or Proterozoic, group, and preceding the Mesozoic group. It comprises the Cambrian, Ordovician, Devonian, Silurian, and Carboniferous systems, and its sediments are the first that contain well-preserved fossils.
Parasitism: A condition in which one organism (the parasite) residing in, or upon, another species of organism (the host) lives at its expense, the relation being detrimental to the latter.
Parthenogenesis: The production of offspring from unfertilized eggs.
Phenotype: The sum-total of external characters by whose enumeration an organism is described—the somatic or expressed characters of an organism (or group of organisms) as distinguished from those that are merely potential in the germ cells.
Phylogeny: Developmental history of the race, the hypothetical evolutionary history of the race, in contradistinction to the embryological development of the individual (ontogeny).
Phylum: A term used in classification to denote any primary group of the plant or animal kingdom.
Plantigrade: Walking on the whole sole of the foot, like bears.
Plastids: Permanent organelles or living components of the cellular cytoplasm,e.g., chloroplasts, leucoplasts, etc.
Pleistocene: The lower series of the Quaternary system of fossiliferous rocks. It corresponds to the so-called Glacial epoch, and extends from the close of the Tertiary period (system) to the dawn of the Recent or Historical epoch.
Polar Cell: A synonym for polar body, or policyte. The polar bodies are minute abortive cells given off by the egg undergoing meiosis. Into them are shunted the chromosomes which the egg discards in its process of nuclear reduction (maturation).
Præformation: Theory that the egg contains a complete miniature of the organism into which it develops.
Prehension: Grasping, catching hold.
Progression: Advancing movement, locomotion.
Pro-simiæ: The lemurs as distinguished from genuine apes (Simiæ).
Protista: Animals or plants which are normally unicellular and which when multicellular show no differentiation into tissues—the Protozoans and Protophytes.
Protoplasm: Living matter.
Receptor: An organ specialized to receive stimuli,e.g., a sense-organ.
Sedimentary: A term applied to rocks which originated as sediments deposited under water.
Serum: Watery portion of the blood, the plasma.
Somatic Cells: Vegetative cells not especially set aside by the organism for reproductive purposes,e.g., tissue-cells.
Somite: One of the uniform segments of the longitudinal series into which a metameric organism (such as an earthworm) is partitioned.
Spermatist: An old term applied to one who held that the animal embryo was produced entirely by the male parent.
Spore: A single cell, incapable of syngamy, but capable of giving rise to a new individual without the sexual process.
Symbiosis: The obligatory association of two organisms of different species for mutual benefit.
Synapsis: Union in pairs of corresponding (homologous) chromosomes of opposite parental origin as a preliminary to their separation in meiosis.
Systematist: An expert in classification (systematics),i. e., a taxonomist.
Taxonomy: The science of classification.
Tertiary Period: A geological time-division corresponding to the rock-system that comprises the greater part of the Cenozoic group. It is made up of four series, namely, the Eocene, Oligocene, Miocene, and Pliocene. Its close marks the beginning of the Glacial or Pleistocene epoch.
Tissue: A layer of uniform cells specialized for the same function.
Tissue Cell: One of the somatic cells of which a tissue is composed.
Troglodytic: Resembling the chimpanzee and the gorilla.
Woods Hole: The seat of the Marine Biological Laboratory. It is a watering-place on the New England coast opposite Martha’s Vineyard.
Zygote: The synthetic cell formed by the union of two gametes and giving rise by division either to a new multicellular organism, or to a rejuvenated cycle of unicellular forms.