THE ATOM 101 



Other elements found in mere traces or large 

 amount in certain organisms are: 



Atomic number Atomic weight 

 Fluorine 9 19. 



Aluminium 13 27.1 



Silicon 14 28.3 



Manganese 25 54.93 



Copper 29 63.57 



Bromine 35 79.92 



Iodine 53 126.92 



These may be of very great importance to the 

 organism. Thus, iodine is stored in the thyroid 

 gland; and metamorphosis in tadpoles was induced 

 by feeding them with traces of inorganic iodine. 

 (Swingle. ^^) In its chemical behavior iodine, as well 

 as fluorine and bromine, shows much resemblance to 

 chlorine. 



Small quantities of cobalt (atomic number 27, 



** See Jacques Loeb, Scientific Monthly, December, 1919. 



