10 THE INTERNAL SECRETIONS—1920 
basic physiologic regulators, the internal secretions, are 
in perfect adjustment—in what might be called a phy- 
sio-chemical equilibrium—those organs will not func- 
tion in harmony. Some or all of them either will run 
too slow or too fast with a resultant state of ill health. 
The most important of the endocrine glands may be 
roughly classed physiologically, thus: 
(1) The Thyroid; metabolism, growth, antitoxic. 
(2) The Adrenals; blood-pressure, arterial tension, 
muscular tone. 
(3) The Pituitary; heart, unstriped muscles, renal 
secretion. 
(4) The Gonads; sexuality, reproduction. 
The secretions they manufacture are called “‘inter- 
nal”’ because they go directly into the circulation with- 
out first being conveyed into other glands or organs or 
undergoing any change. Hence, they are internal with 
reference to the blood current. 
Speaking in a general way, the adrenals and pitu- 
itary control the action of the heart. Either a hyper- 
or hypo-function of these glands will disturb the sta- 
bility of its action. Either it will lose its normal power 
of contraction, become enfeebled—blood-pressure low, 
circulation retarded, extremities cold, more or less 
edema of the lungs and viscera—hence, difficult res- 
piration and imperfect digestion; or else the heart will 
contract with too much force—the blood pressure is 
high, skin flushed, high nervous tension, headache more 
or less constant, apoplexy threatening. Such are the 
chief symptoms of adrenal dysfunction. 
To the consideration of these two, let us add another, 
the thyroid. This gland, taken in connection during 
early life with the thymus, influences the growth and 
development both physical and mental of the child. 
During adult life it continues to influence metabolism; 
also, it has remarkable antitoxic action. Therefore, 
the grave pathological effect of any disturbance of its 
