Mutation (change), has now two accepted meanings: (1) a profound change in the germ-plasm of an organism such as will produce numerous changes in its progeny; and (2) a discontinuous heritable change in a Mendelian factor. It is used in the first sense by De Vries and other "mutationists" and in the second sense by Morgan and other Mendelists; confusion has arisen from failure to note the difference in usage.
Normal Curve, the curve of distribution of variations of something whose variations are due to a multiplicity of causes acting nearly equally in both directions. It is characterized by having more individuals of a mediocre degree and progressively fewer above and below this mode.
Nucleus (little nut), a central, highly-organized part of every living cell, which seems to play a directive rôle in cell-development and contains, among other things, the chromosomes.
Patent (lie open), a term applied to traits which are manifestly represented in the body as well as the germ-plasm of an individual. The converse of "latent."
Probability Curve, the same as normal curve. Also called a Gaussian curve.
Protoplasm (first form), "the physical basis of life"; a chemical compound or probably an emulsion of numerous compounds. It contains proteins which differ slightly in many species of organism. It contains carbon, hydrogen, oxygen, nitrogen, sulphur, and various salts, but is so complex as to defy exhaustive analysis.
Psychiatry (soul healing), the study of diseases of the mind.
Recessive (draw back), the converse of dominant; applied to one of a pair of contrasted Mendelian characters which can not appear in the presence of the other.
Regression (back go), the average variation of one variable for a unit variation of a correlated variable.
Segregation (aside flock), (1) as used in eugenics means the policy of isolating feeble-minded and other anti-social individuals from the normal population into institutions, colonies, etc., where the two sexes are kept apart. (2) The term is also used technically in genetics, to refer to the discontinuity of the variation of characteristics resulting from the independent distribution of factors before or at the time of formation of the gametes.