an insufficient performance of it; and this, by closing an avenue of elimination, poisons the blood, and depraves the organization. The host of ills thus induced are known to physicians and to the sufferers as amenorrhoea, menorrhagia, dysmenorrhoea, hysteria, anemia, chorea, and the like. Some of these fasten themselves on their victim for a lifetime, and some are shaken off. Now and then they lead to an abortion of the function, and consequent sterility. Fortunate is the girls' school or college that does not furnish abundant examples of these sad cases. The more completely any such school or college succeeds, while adopting every detail and method of a boy's school, in ignoring and neglecting the physiological conditions of sexual development, the larger will be the number of these pathological cases among its graduates. Clinical illustrations of these statements will be given in another place. The mysterious process which physiologists call metamorphosis of tissue, or intestitial change, deserves attention in connection with our subject. It interests both sexes alike. Unless it goes on normally, neither boys, girls, men, nor women, can have bodies or brains worth talking about. It is a process, without which not a step can be taken, or muscle moved, or food digested, or nutriment assimilated, or any function, physical or mental, performed. By its aid, growth and development are carried on. Youth, maturity, and old age result from changes in its character. It is alike the support and the guide of health convalescence, and disease. It is the means by which, in the human system, force is developed, and growth and decay rendered possible. The process, in itself, is one of the simplest. It is merely the replacing of one microscopic cell by another; and yet upon this simple process hang the issues of life and death, of thought and power.