FUNCTIONS OF THE BLOOD 273 



hormone useful in maintaining the nutrition of the muscular and 

 nervous systems. Over-development of the anterior lobe of the 

 pituitary body in man has been found to be associated with the 

 curious condition named acromegaly, in which there is hypertrophy 

 of the bones of the limbs and face. It will be noted that this 

 disease, acromegaly, is essentially one of overgrowth, and since 

 it is associated with an enlargement of the gland is probably the 

 result of over-stimulation of the growth process through too 

 abundant production of the hormone. This idea is borne out by 

 observations of conditions in which the hormone is deficient. 

 When this occurs there is an excessive tendency to lay on fat, 

 suggesting that materials which would normally be used for 

 tissue growth are not called for by the tissues and so are stored in 

 the form of fat. Failure of development of certain organs, not- 

 ably those of generation, also results from a deficiency of the 

 hormone. 



The Suprarenal Capsules or Adrenals are a pair of small organs, 

 weighing together about 12 grams (J oz.) placed one on the top 

 of each kidney. They have, however, no intimate connection 

 with the kidneys, and in many animals are placed at some dis- 

 tance from them. Each consists of a denser less colored external 

 cortex, and a central deep yellow-brown softer medulla. The cor- 

 tex is subdivided into chambers by connective tissue, and the 

 chambers are filled by closely packed, polygonal nucleated cells. 

 Similar cells are found in the medulla, which is, moreover, closely 

 connected with the sympathetic system and is richly supplied 

 with nerves. 



It was noticed some seventy years ago by a physician named 

 Addison that certain obscure diseased conditions characterized by 

 great debility and by the appearance of bronzed patches on the 

 skin, and leading to death, were found on post-mortem examina- 

 tion to be accompanied by disease of the adrenals. The disease 

 has since been named Addison's disease. When the suprarenal 

 capsules are completely removed from animals a similar fatal 

 diseased condition results, death taking place in warm-blooded 

 animals within two or three days, and being preceded by muscu- 

 lar weakness, dilatation of the arteries, mental feebleness and 

 general prostration. A substance of comparatively simple chem- 

 ical composition, known as adrenalin, can be obtained from the 



