EXPERIMENTATION AND PHYSIOLOGY 



slowly but surely by physiologic experiments. Internal 

 It is discovered that all of the glandular struc- secretions, 

 tures supply certain substances to the blood 

 which are essential to the economy of the 

 organism and which are independent of the 

 gross secretions which were first studied. The 

 pancreas, the kidneys, the female breasts, the 

 ovaries, the testicles, among the organs which 

 have a special secretory function; and the 

 thyroid, the spleen, the pituitary body and 

 the suprarenal capsules, among the ductless 

 glands, all have their important internal 

 secretions. The removal or destruction by dis- 

 ease of a certain amount of these organs is 

 followed by constitutional disturbances. 



The thyroid glands, two small bodies lying 

 in the neck on either side of the trachea, may 

 be taken as examples of the ductless glands, 

 i. e., glands which do not produce a fluid which 

 is emptied out through a tube into some hol- 

 low viscus. They were originally thought to 

 be unimportant and not to have any function. 

 Then about fifty years ago the physiologist 

 Schiff reported that when the thyroids are 

 removed from dogs the dogs die with certain 

 peculiar symptoms. Twenty-five years later 

 the Swiss surgeon, Kocher, to whom has just 



43 



