380 



HUMAN PHYSIOLOGY 



looking at such an arrangement. Four small nodules 

 of a distinctive tissue, unlike that of the main thyroid, 

 are found imbedded in it or close by. These kernels are 

 the parathyroids, and there is no doubt that they send 

 out a valuable hormone. In their absence convulsive 

 disturbances of the skeletal muscles occur. 



The Adrenals. These are two small bodies which are 

 placed above the kidneys. The fact that they are neces- 

 sary to life has long been known. If they are wasted by 

 disease, as by a localized tuberculosis, one or more in- 

 dispensable hormones seem to be lost. The victim grows 



FIG. 79. The adrenals (n,n), surmounting the kidneys and close 

 under the diaphragm. 



weak, suffers from incessant nausea, and dies as though 

 from exhaustion. An incident of the decline is a dark 

 pigmentation of the skin which has given the derange- 

 ment the name of Addison's bronze disease. Dogs de- 

 prived of the adrenals soon die. 



An extract of the adrenal body has extremely active 

 properties, but it has not found its chief use in the cor- 

 rection of Addison's disease, as might be inferred from 

 the account of the thyroid. The adrenal extract is sold 

 under the name of adrenalin. It contains a substance 

 which can be isolated and which is responsible for most 

 of the powers of the extract; it is called adrenin or epi- 



