108 THE GLANDS REGULATING PERSONALITY 



reins of the drive or check systems in the vegetative apparatus. 

 Together with the other ductless glands, they decide the advance 

 or halt, forward or retreat, tension or relaxation, charge and dis- 

 charge, of the visceral — involuntary muscle — blood vessel com- 

 bination which is at the core of life. Here again they emerge as 

 the directorate. 



Carlson, the Chicago physiologist, who probably knows more 

 about being hungry than any other man on the planet, once 

 demonstrated that the injection of an ounce -or two of the blood, 

 which means the internal secretion mixture, of a starving animal, 

 into one not starving increased the signs of hunger and the ac- 

 companying hunger contractions of the stomach. There can be 

 no doubt that hunger is the expression of a certain specific con- 

 centration of internal secretion or secretions in the blood. When 

 the quantity, in the cycles of metabolism, becomes sufficiently 

 great, it stimulates the stomach to contract in a way which 

 augments the pressure within it to a point at which the feeling 

 of hungriness, and the wish to satisfy it, or to get rid of it, 

 becomes imperative, and the dominant of consciousness. 



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 manufac- 

 tured 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 intra- 

 visceral 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 compre- 

 hensible mechanism conceivable that will fit all the known facts 

 about the matter. And even though the assertions of Brown- 

 Sequard were only the exaggerations of a semi-charlatan, it is 

 certain that some day in the near future the particular sub- 

 stance, 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 secre- 



