Restrictive (or negative) Eugenics, a system of improving the human race by preventing reproduction of the unfit.
Reversion (L. re, back; verto, turn), the reappearance of ancestral traits which have for some generations been in abeyance.
Rheotropism (Gr. rheo, to flow; tropē, turning), defined, [p. 198].
Salpingectomy (Gr. salpinx, trumpet; ectomē, cutting out), removal of part or all of a Fallopian tube (oviduct).
Segregation (L. se, aside; grex, flock), separation.
Sex Chromosome, a special chromosome which is supposed to be concerned in the determination of sex.
Sex-Linked Characters, defined, [p. 60].
Simian (L. simia, ape), ape-like.
Simplex (L. sim, same; plico, fold), the condition in which a character is represented by a determiner from only one of the two parents.