SIMPLEX (L. _sim_, same; _plico_, fold), the condition in which a character is represented by a determiner from only one of the two parents.
SOMA (Gr. _soma_, body), the body considered apart from the germ-cells.
SPERMATID (Gr. _sperma_, seed), a cell resulting from the last division of the germ-cell in spermatogenesis. It transforms into the spermatozoon.
SPERMATOCYTES (Gr. _sperma_, seed; _kytos_, cell), cells concerned in the maturation divisions of the male germ-cells.
SPERMATOGENESIS (Gr. _sperma_, seed; _genesis_, origin), the development of spermatozoa from primitive s.e.x-cells.
SPERMATOGONIUM (Gr. _sperma_, seed; _gonos_, generation), a primordial sperm-cell.
SPERMATOZOON (Gr. _sperma_, seed; _zoon_, animal), the functional male s.e.x-cell.
SPINDLE, a fibrous organ formed in indirect cell-division.
SPIREME (L. _spira_, coil), a characteristic stage preliminary to indirect cell-division in which the chromatin material of the nucleus appears in the form of a skein of filaments.
STEREOTROPISM (Gr. _stereos_, solid; _trope_, turning), defined, p. 198.
STERILIZATION (L. _sterilis_, barren), deprivation of reproductive power.
For methods, see p. 322.
SYNAPSE (Gr. _syn_, together; _hapto_, unite), the coming in contact of the processes of one nerve cell with the processes or body of another.
SYNAPSIS (Gr. _syn_, together; _hapto_, unite), union of the chromosomes in pairs preliminary to the reduction division.
TELEGONY (Gr. _telegonos_, born far away), the supposed influence of an earlier sire on offspring born later of the same mother to a different sire.
THERMOTROPISM (Gr. _thero_, heat; _trope_, turning), defined, p. 198.
THIGMOTROPISM (Gr. _thigmo_, touch; _trope_, turning), defined, p. 198.
TOXIN (Gr. _toxicon_, poison), poisonous compounds of animal, vegetable, or bacterial origin.
TROPISM (Gr. _trope_, turning), the automatic directing of an organism toward or away from a source of stimulus.
UNIT-CHARACTER, a character which behaves as an indivisible unit in heredity.
VASECTOMY (L. _vas_, vessel; _ektome_, cutting out), removal of a portion of the vas deferens (duct for conveying spermatozoa).
VESTIGEAL (L. _vestigium_, footstep), representing organs which existed once in a more developed condition.
VOLVOX (L. _volvo_, roll), a small fresh-water organism occurring in spherical colonies.
Wa.s.sERMAN REACTION, a test for syphilis, see p. 188.
X-ELEMENT, same as s.e.x-chromosome.
ZYGOTE (Gr. _zygon_, yolk), the product of the union of two gametes.
REFERENCES FOR FURTHER READING AND STUDY
BATESON, W., 1909. _Mendel"s Principles of Heredity._ Cambridge, The University Press. The best technical account of Mendelism. It contains also a translation of the original papers of Mendel.
CASTLE, WILLIAM E., 1911. _Heredity._ New York, D. Appleton and Company.
CASTLE, WILLIAM E.; COULTER, JOHN M.; DAVENPORT, CHARLES B.; EAST, EDWARD M.; TOWER, WILLIAM L., 1912. _Heredity and Eugenics._ Chicago, The University of Chicago Press.
CONKLIN, EDWIN GRANT, 1915. _Heredity and Environment in the Development of Men._ Princeton, Princeton University Press.
DAVENPORT, CHARLES B., 1911. _Heredity in Relation to Eugenics._ New York, Henry Holt and Company.
DONCASTER, L., 1911. _Heredity in the Light of Recent Research._ Cambridge, The University Press.
DONCASTER, L., 1915. _The Determination of s.e.x._ Cambridge, The University Press.
ELLIS, HAVELOCK, 1912. _The Task of Social Hygiene._ New York, Houghton Mifflin Company.
GALTON, FRANCIS, 1869. _Hereditary Genius: an Inquiry Into Its Laws and Consequences._ London, Macmillan and Company.
GALTON, FRANCIS, 1889. _Natural Inheritance._ New York, The Macmillan Company.
GALTON, FRANCIS, 1895. _English Men of Science; Their Nature and Nurture._ New York, D. Appleton and Company.
GALTON, FRANCIS, and SCHUSTER, EDGAR, 1906. _Noteworthy Families_ (Modern Science). London, J. Murray.
G.o.dDARD, HENRY HERBERT, 1912. _The Kallikak Family; a Study in the Heredity of Feeble-mindedness._ New York, The Macmillan Company.
G.o.dDARD, HENRY HERBERT, 1914. _Feeble-mindedness; Its Causes and Consequences._ New York, The Macmillan Company.
HEALY, WILLIAM, 1915. _The Individual Delinquent._ Boston, Little, Brown and Company.
KELLICOTT, WILLIAM E., 1911. _The Social Direction of Human Evolution; an Outline of the Science of Eugenics._ New York, D. Appleton and Company.
MORGAN, THOMAS HUNT, 1913. _Heredity and s.e.x._ New York, Columbia University Press.
PUNNETT, R. C., 1911. _Mendelism._ New York, The Macmillan Company. The best popular account of Mendelism.
SALEEBY, CALEB WILLIAM, 1909. _Parenthood and Race Culture; an Outline of Eugenics._ London, Ca.s.sell and Company.
SCHUSTER, EDGAR, 1912. _Eugenics._ London, Collins Clear-Type Press.
THOMSON, J. ARTHUR, 1908. _Heredity._ London, John Murray.
WALTER, HERBERT EUGENE, 1913. _Genetics._ New York, The Macmillan Company.