Sedatives. Medicines which allay irritation or irritability of the nervous system.

Sedentary. Requiring much sitting.

Self-pollution. See Self-abuse.

Semen. The secretion of the testicles which is thrown out during sexual intercourse and contains the principle of generation.

Semi-fluid. Half fluid.

Semilunar Valves. Valves in the heart. See 9 and 17, Fig. 41, [page 58].

Seminal vesicles. Reservoirs for the sperm. See Seminal Sac, on [page 207].

Septic. That which corrodes or produces putrefaction.

Septicæmia. Blood-poisoning; usually by absorption.

Sequel. That which follows; the condition or malady which follows a disease.