What concerns us now is its internal secretion or secretions.  One of them is known as lutein and it has never been chemically isolated in its pure form.  The existence of lutein, like the existence of electricity, is an inference, something we are sure is there because of its effects.  It originates in a remarkable part of the ovary, the corpus luteum.  Besides, there are the products of the interstitial cells, the creations of a special layer of cells around the ovum, the membrana granulosa.  They produce a substance tonic to the uterus.

When the ovaries are removed, there occurs an atrophy of the womb muscle, due to loss of this tonic substance.  This atrophy, accompanied by an abolition of the normal periodic uterine contraction, makes conditions unfavorable to pregnancy.  It has been claimed that the secretion of the corpus luteum is necessary for the complete progress of a pregnancy.  Cases are on record, however, of ovaries taken out soon after the onset of pregnancy, without interference with the gestation.

Castration is comparable in every way with the menopause or the time of cessation of sexual life, a process that might be called self-castration.  It produces certain general constitutional effects.  Adiposity often develops, undoubtedly associated with underfunction of the thyroid and pituitary glands.  The woman breathes less oxygen per minute and burns up less food and tissue.  There is some disturbance of the lime balance with an increased excitability of the vegetative nervous system.  Concomitant is the release of some brake upon the blood pressure mechanisms, so that a family tendency to high blood pressure will flare up.  Some women are rendered unstable by the process, others are completely transformed, and still others adapt themselves, with little or no discomfort, to the new situation.  The response to the revolution in the cell-republic of the castrate by the other endocrines, the thyroid, the pituitary, and the adrenals, determines which it is to be.

For normally, with feminine puberty, there is an increased activity of the thyroid, the posterior pituitary and the adrenal medulla.  These changes indeed constitute the formula of normal feminization.  In the male, the ripening of the testes is accompanied or perhaps preceded by augmented function of the adrenal cortex and the anterior pituitary.  This difference in biochemistry accounts for the contrast between the sexes in the skin, hair, fat, cartilage (voice) and bone changes.  Ovary and adrenal medulla and posterior pituitary and thyroid predominance constitute the feminine formula.  Testis and adrenal cortex and anterior pituitary predominance comprise the masculine endocrine directorate.

THE REACTIONS OF THE OTHER GLANDS

As in so many other aspects, the facts about the various influences exerted by the endocrine glands upon the reproductive system are complicated and disjointed.  A chink of light has been let in upon a dark cave, and slowly the chink will widen.  But the gross effects are clear.