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).