BIOELEMENTS; THE CHEMICAL ELEMENTS OF LIVING 



MATTER. 



By INGO W. D. HACKH. 



{From the College of Physicians and Surgeons, San Francisco?) 



(Received for publication, November 25, 1918.) 



Among the 87 known elements less than one-half (namely 34) have 

 been found to enter into living matter. Of these only 17 seem to be 

 essential to life, and of these 17 not more than 4 elements form from 

 97 to 99 per cent of the living organism. 



In order to illustrate the importance of the different elements Fig. 

 1 and Tables I and II have been prepared, showing that some ele- 

 ments occur invariably, others frequently, and still others are of such 

 rare occurrence that their presence in living matter seems adventitious. 



In Fig. 1 the new periodic system'^ has been utilized to show that 

 all the bioelements occupy neighboring places and that the majority of 

 them possess low atomic weights, belonging to the first two periods 

 of the system. 



An approximation to the ultimate composition of man is given 

 in Column 2 of Table I, while Column 3 shows the elementary 

 composition of long leaf pine, calculated from the data of Little.^ 

 The chemical character of the mammal in comparison with the gym- 

 nosperm is evident, the latter containing 99 per cent of C, H, and 

 and only very small amounts of other elements, of which Al and Si 

 are the predominant ones (due to the abundance of these two elements 

 in the soil). 



With the exception of oxygen, no element enters into the living 

 organism as a free element, but only in the form of compounds, the 

 majority of these being non-polar; that is, organic compounds. For 



1 Hackh, I. W. D., /. Am. Chem. Soc, 1918, xl, 1023; Am. J. Sc, 1918, xlvi, 

 481. 



^ Little, A. D., /. Ind. and Eng. Chem., 1916, viii, 102. 



429 



