The difference between the thyroid and the pituitary might be put this way: that while the thyroid increases energy evolution and so makes available a greater supply of crude energy, by speeding up cellular processes, the pituitary assists in energy transformation, in energy expenditure and conversion, especially of the brain, and of the sexual system. In short, the thyroid facilitates energy production, the pituitary its consumption. The pituitary appears therefore as the gland of continued effort. Hence fatigability, an inability to maintain effort, is one of the prominent complaints when there is destruction or an insufficiency of it for one reason or another. As such, it contrasts with the glands of emergency effort, known as the adrenals. CHAPTER III THE ADRENAL GLANDS, THE GONADS, AND THYMUS Like the pituitary, each adrenal gland is a double gland, that is, consists of two distinct portions, united together, one might say, by the accident of birth. It would be confusing, however, to speak of each as two glands, because there are, as a matter of fact, two separate adrenal glands, one in the right side of the abdomen, and the other in the left. Each gland is composite, or duplex. How the two parts came to be united is a long story, interesting but too long to be recounted here. In fishes they are apart and independent. Each adrenal is a cocked hat shaped affair, astride the kidneys, easily recognized because of its yellowish fatty color. Indeed, for centuries the glands were not given a separate status as organs, but were passed up as part of the fat ensheathing the kidney. In childhood and youth, in common with the other glands, they are relatively larger and more prominent than in the adult. Also, at every age, the amount of blood passing through them is very large compared to their size. Their tremendous importance in the body economy accounts for their being so favored. The two parts of which each gland is composed, are known as the cortex or outer portion (literally the bark) and the medulla or inner portion (literally the core). No clean-cut boundary sharply delimits the two, as strands and peninsulas of tissue of one portion penetrate the other. In the history of their development in the species and the individual, and in their chemistry and function, a sharp difference contrasts them.