DUCTLESS GLANDS 167 



of extrsme nervousness, with loss of weight and other symptoms, 

 such as protruding eyeballs and irregular heart action. The 

 thyroid evidently has much to do in regulating the metabolic 

 processes within the cells of the body. 



The Adrenals (Suprarenals). — The adrenals, or suprarenals, 

 form substances which act upon the muscles and the nervous sys- 

 tem. The hormone known as adre'nine causes a faster beating of 

 the heart, a heightened blood pressure, and other indications of 

 increased muscular activity. It is indeed the emergency hormone 

 of the body. It is this hormone that enables the sprinter to make 

 his final burst of speed at the tape, or the football player to make a 

 desperate stand when almost exhausted. It explains the '^ strength 

 of desperation." Adre'naline, an artificial adrenine made by 

 chemists, is used in medicine to contract the blood vessels and 

 hasten the clotting of blood, and in other ways. 



The Thymus and Pituitary. — The thymus gland, which grows 

 smaller or disappears in adult life, seems in some way to regulate 

 body growth and metabolism. The pituitary gland also has much 

 to do with body size, as dwarfs appear to lack this gland, while in 

 giants it seems always abnormally large. Dr. Harvey Gushing of 

 the Harvard Medical School, who is an authority on the work of 

 the pituitary body, says : '' The Lewis Garroll of to-day would 

 have Alice nibble from a pituitary mushroom in her left hand and 

 a lutein [a pigment obtained from a portion of the ovary] in her 

 right hand and presto ! she is any height desired." 



The Reproductive Glands. — Some part of the ovaries and testes 

 have long been known to control the so-called secondary sex charac- 

 teristics which give us the outward appearance of females or males. 

 It is not too much to say that hormones are responsible for many 

 sex characteristics, as experiments with fowls and other animals 

 have proved. But popular statements on the effect of grafting 

 glands from other animals in human beings are greatly exaggerated 

 and can be for the most part disbelieved. 



The Pancreas and Liver. — It has been known for many years that 

 the pancreas produces another secretion besides that which passes 

 into the digestive tract. But only recently has it been discovered 

 that this internal secretion, with its hormone, is produced in 

 groups of cells known as the Islands of Langerhans (lang'er-hans) 



