The fundamental sex of the individual, chromosomal sex, is determined at the moment of conception by the type of sex chromosome carried by the male sperm cell. All eggs have the X chromosome. At top, the XX combination means a female. The black mass at top right is the sex chromatin, found in the nucleus of the female cell only. The XY combination, shown below, means a boy.—After Modern Medicine.

known as undrogens and are se- creted by the testicles and by the adrenal glands. The ovaries are the principal source of the "fe- male hormones," the most impor- tant being estrogen.

Both sex hormones androgen as well as estrogen are present in both sexes, but androgen dom- inates in men, estrogen in women. The sex hormones promote the development of the secondary sex characters and preserve them throughout life.

Their importance for the per- sonality justifies the term En- docrine Sex, as the fourth in our series. The endocrine sex is not linked to the sex glands only. Other glands likewise supply hor- mones, essential for both sexes in maintaining their complete sex status.

Just as the anatomical sex is never purely male or purely fe- male (remember the nipples in men and the rudimentary penis called clitoris in women), so is the endocrine sex "mixed" to an even greater extent.

If we want to be technical, we must admit, with scientific justifi- cation, that we are all anatomical- ly as well as endocrinologically "intersexes." But we are male or female in the anatomical or en- docrine sense, according to the predominant structures or hor-

mones.

Actually an abundance of andro- gen seems to go with greater mas- culinity, an abundance of estro- gen with more femininity.

Men have varying amounts of both sex hormones, and so have women, determining to some ex- tent their appearance and their behavior. More or less distinct changes can be brought about by artificially increasing or decreas- ing the amount of hormones in a person, especially if the normal ratio between androgen and estro- gen is altered and with it the char- acter of the person's endocrine

sex.

It must be remembered and again emphasized, however, that the genetic sex comes first, the endocrine sex merely being the re-

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