MATERIAL RESOURCES OF LIFE. 337 



In this bed the tusk was found. Several feet of obsoletely stratified drift 

 sand, with pebbles and boulders are found in the gully below this. 



CHEMISTRY. 



THE MATERIAL RESOURCES OF LIFE.* 

 BY ALBERT B. PRESCOTT. 



To be able to live, in any way known to us, it is indispensable to have cb 

 body. And, as living bodies come by growth and continue by nourishment, 

 it is first necessary to have materials whereof bodies can be made — and 

 renewed and kept in warmth and strength. Just these materials, with the 

 permission of the reader, we will try to take account of, as resources of life. 

 Life is not maintained "by bread alone;" other needful resources being- 

 known to physical science, and still other resources greater than all being 

 recognized by their results in life; but we have the bread alone, as enough, 

 certainly, to be considered in the present article. 



Living things are in very deed made of "the dust of the earth;" but it 

 is by no means all of the dust of the earth that serves this purpose. We 

 have to distinguish between substances out of which organized instruments 

 of life can be made, and a much larger number of substances never used in 

 the making of these instruments. 



We have it in mind that matter is made up of sixty-three simples. At 

 all events, the earth's crust and air are constituted, substantially, of these 

 sixty-three sorts of atoms, and, as a good many of the same are already re- 

 vealed in the sun and stars by the spectroscope, it is likely that they are 

 the chief elements in the universe of matter. Of the sixty-three, certain 

 elements, foiind only in very small quantities, appear to be of subordinate 

 importance in that part of the universe under our immediate observation, 

 whatever purposes they may fulfill in other earths or in the centre of our 

 own, or at other epochs. Others of the elements bear an important part in 

 the structure of the globe or in the uses of mankind, but are not orgaa- 

 izable materials, and they are not in our jDresent consideration. Of the 

 sixty-three, only fourteen or fifteen simples, about one-fourth of those 

 known to us, are used in the construction of plants and animals. These, 

 then, are before us, as the elemental resources of life. 



It will be understood that the tissues are not built directly of these 

 fourteen elements, but of their chemical compounds. Each one of these 

 compounds is a definite substance in external character distinct from its 



••'An acl"dress given before the Detroit Scientific Association, December 13, 187G. 



