REGULATION OF CELL ACTIVITIES 193 



HI 

 C 



/ \ H H 



V-/ V-/ ' v-' " v> 



H H 



HIC C C =? O 



\ //\s 



C N 

 H H 

 and 



HI 

 C 

 / \ H H 



-tj.J.v./' V^ V-* V-/ ~ J v- 



H H 

 HC C C OH 



O 



OH 



C 

 OH 



C N 

 H 



as well as an open ring structure. 

 HI 

 C 



/ \ H H 



HIC C C C C C/ 

 H H \ 



HIC 



O 

 OH 



C = O 



\s\ I \ 



C N O 



H /\ H 



H H 



This substance contains as much as 58-60 per cent, of iodine. 

 ADRENAL GLANDS 



These are another interesting example of internally secreting 

 glands. In 1855 Addison showed that a disease characterised 

 by muscular weakness and bronzing of the skin was associ- 

 ated with tuberculous disease of the adrenal glands.* 



Oliver and Schafer showed that injections of extracts of 

 the adrenal glands caused a marked rise in blood pressure, 

 which is due mainly to constriction of the blood vessels, f 



* T. Addison, On the Constitutional and Local Effects of Disease of 

 the Suprarenal Capsules. London, 1855. 



t G. Oliver and E. S. Schafer, Journ. Physiol., 1895, vol. 18, p. 230. 

 13 



