Without doubt the sexual cravings are likewise so determined. Sex libido is an expression of a certain concentration, a definite amount peculiar to the individual, of the substance manufactured by the interstitial cells, circulating in the blood. It arouses its effects probably by (1) increasing the amount of reproductive material in the sex glands in a direct chemically stimulating effect upon the germinative cells, and so raising the internal pressure within them, (2) stimulating the involuntary muscles within the walls and the canals of the sex glands, and so, by augmenting the tenseness of the muscles, elevating the total intravisceral pressure, (3) by a direct chemical and indirect nervous effect upon the brain, the muscles, the heart, as well as the other glands of internal secretion stimulating the organism as a whole. Though the isolation in pure form of the substance or substances involved has never been scientifically achieved, their inference is entirely justified. It is indeed the only comprehensible mechanism conceivable that will fit all the known facts about the matter. And even though the assertions of Brown-Séquard were only the exaggerations of a semi-charlatan, it is certain that some day in the near future the particular substance, that he claimed he had discovered, will be handed about in bottles for the inspection of the curious.
Besides thyroxin, adrenalin, and the libido-producing secretion of the interstitial cells, the substance produced by the paired glandlets, situated behind the thyroid, the parathyroids, have a profound influence upon the vegetative apparatus and the vegetative nervous system. These direct the lime exchanges within the cells of the organisms, including the nerve cells. It has been shown that lime is, relatively, a sedative to cells. It raises the threshold or strength of stimulus necessary to evoke a reaction. Removing the parathyroids means removing the lime barrier, for with their deficiency there is a change in, and then an escape, from the blood, of the lime, by way of the kidneys. The result is sometimes an enormous increase in the excitability of all the cells, and especially of the vegetative apparatus. What that means for the individual whose comfort depends upon a stability of the intravisceral tones and pressures may be readily imagined.
The pancreas likewise acts as a sedative to the vegetative apparatus. In particular, this applies to the sugar mechanism in the liver under the discipline of the check and drive organization. The adrenal and the pancreas are the direct antagonists in the struggle for control of sugar. Removal of the adrenals will cause a decrease in the amount of sugar in the blood, while removal of the pancreas will produce an increase. Excess of sugar in the blood may thus be concomitant with changes of character considered incorrigible.
In different locales of the vegetative apparatus, as indeed of the body in general, the directorate seems to be handed over to a committee of control, generally made up of two members working in opposing directions. Such a division of power in the general directorate is analogous to the small holding corporations which divide functions in, for example, the United States Steel Corporation. The relative ratios of tonus in these smaller internal secretion balances are of the utmost significance as causes of differences in the vegetative apparatus, which are the basis of differences in structure, power, and character between individuals.
THE GENERAL LAWS OF THE DIRECTORATE
Our knowledge of the glands of internal secretions as an interlocking directorate presiding over all the functions of the organism is still exceedingly meagre. As yet, we seem to be knocking at the portals of the chemistry of the imponderable. There are holes in the bronze doors, and we glimpse the unfathomable distances of unexplored regions. But we do see something, and we do glimpse a beginning. Already the outlines of a differential anatomy, and a different physiology and a differential psychology, which will explain to us the unique in the constitution, the temperament and character of an individual, emerge. It is worth while, before proceeding to the details, so valuable to a society which would become rational, to summarize the general principles emerging, expressing the directing powers of the ductless glands over the individual. They may be regarded as the present postulates of a new science of the whys and wherefores separating and setting apart, as so recognizably distinct, those peregrinating chemical mixtures: men and women.
1. The life of every individual, in every stage, is dominated largely by his glands of internal secretion. That is, they, as a complex internal messenger and director system, control organ and function, conduct and character. The orderliness of human life, in the sequential march of its episodes, crises, successes and failures, depends, to a large extent, upon their interactions with each other and with the environment.
2. One or several of the glands possesses a controlling or superior influence above that of the others in the physiology of the individual and so becomes the central gland of his life, its dominant, indeed, so far as it casts a deciding vote or veto, in its everyday existence and incidents as well as in its high points, the climaxes and emergencies.
3. These glandular preponderances are at the basis of personality, creating genius and dullard, weakling and giant, Cavalier and Puritan. All human traits may be analyzed in terms of them because they are expressions of them.
4. Specific types of personality may be directly associated with particular glandular prominences, so that we have the thyroid-centered types, the pituitary-centered types, the adrenal-centered types, etc. These are the classic Three, the prototypes in their purity most easily described and recognized.