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PSYCHOBIOLOGY 



All of these ductless glands are supplied with nerves which apparently 

 are mostly from the sympathetic system, although there are also fibers 

 from the vagus, cervical and sacral autonomic nerves. The nerve supply 

 to the adrenal glands is so rich that these organs have formerly been sup- 

 posed to belong to the sympathetic nervous system. Some of the nerve 

 fibers terminate in connection with the blood vessels, and some in connec- 



FlG. 81. The thyroid and thymus glands in a child of six months. (Schafer, 

 Microscopic Anatomy, after Sappey.) A. The positions of the thyroid and thymus 

 glands: I, 2, and 3, right and left lobes and median fissure of the thymus; 6, thyroid; 

 9, common carotid artery; 10, internal jugular vein; 5, 7, and 8, veins. B. Right lobe 

 of thymus, with envelope removed. C. The lobe, unravelled, showing the strand of 

 connective tissue along which the lobules are grouped. 



tion with the secreting cells. Whether there are any sensory fibers is not 

 known. 



The secretion of the thyroid gland has an important influence on the 

 growth of all the bodily tissues. In cases of removal of the thyroid gland 

 a condition known as myxedema ensues; the metabolic processes proceed 



