THE LIVING ORGANISM 235 



tion of the hormones is slower than that 

 of the nervous system, but more detailed 

 and complete. 



There exist in the body a number of glands 

 with no external secretions or obvious uses 

 which were a great mystery to the earlier 

 anatomists and physiologists, who called them 

 " bodies " or " capsules," and left the matter 

 at that. The chief of these are called the supra- 

 renals, the thyroids, the para- thyroids, and 

 the pituitary. It is now known that these 

 are active secreting glands, and in spite of 

 their small size and obscurity of function, 

 are absolutely essential to the life of the 

 animal. Their removal invariably causes 

 death in a few days to a few months' time, 

 and any marked disturbance of their function 

 in the direction either of excess or defect 

 produces profound disease often of a fatal 

 character. 



The investigation of the uses of the supra- 

 renals, two minute glands not over an ounce 

 in weight, lying in the body just above the 

 kidneys, but in no functional way connected 

 with them, may be taken briefly as an example. 

 The first step was made by a physician of 

 Guy's Hospital, named Addison, who showed 

 that a disease since called Addison's disease, 

 was related to a diseased condition of the 



