IRON IN THE LIVING BODY. 807 



Antilles, and continue to multiply like our American pension claim- 

 ants. The hunters of those jungle woods, indeed, must often smile 

 to remember the complaint of the early settlers that the pleasure of 

 the chase in the West Indian wilderness was modified by the scarcity 

 of four-footed game, and in the total number (as distinct from the 

 number of species) of wild or half-wild mammals Cuba and Hayti 

 have begun to rival the island of Java. 



[ To be continued. ] 



IKON IN THE LIVING BODY. 



By M. A. DASTRE. 



TKON occurs, in small and almost infinitesimal proportions, in 

 -L numerous organic structures, in which its presence may usually 

 be detected by the high color it imparts; and in the animal tissues 

 is an important ingredient, though far from being a large one. It 

 is essential, however, that the animal tissues, and particularly the 

 liquids that circulate through them, should be of nearly even weight, 

 else the equilibrium of the body would be too easily disturbed, and 

 disaster arising therefrom would be always imminent. Hence the 

 iron is always found combined and associated with a large accompani- 

 ment of other lighter elements which, reducing or neutralizing its su- 

 perior specific gravity, hold it up and keep it afloat. Thus the molecule 

 of the red matter of the blood contains, for each atom of iron, 712 

 atoms of carbon, 1,130 of hydrogen, 214 of nitrogen, 245 of oxygen, 

 and 2 of sulphur, or 2,303 atoms in all. Existing in compounds of 

 so complex composition, iron can be present only in very small pro- 

 portions to the whole. Though an essential element, there is compara- 

 tively but little of it. The whole body of man does not contain more 

 than one part in twenty thousand of it. The blood contains only five 

 ten-thousandths; and an organ is rich in it if, like the liver, it con- 

 tains one and a half ten-thousandths. "When, then, we seek to repre- 

 sent to ourselves the changes undergone by organic iron, we shall 

 have to modify materially the ideas we have formed respecting the 

 largeness and the littleness of units of measure and as to the meaning 

 of the words abundant and rare. We must get rid of the notion that 

 a thousandth or even a ten-thousandth is a proportion that may be 

 neglected. The humble ten-thousandth, which is usually supposed 

 not to be of much consequence, becomes here a matter of value. 

 Chemists working with iron in its ordinary compounds may consider 

 that they are doing fairly well if they do not lose sight of more than 

 a thousandth of it; but such looseness would be fatal in a biological 



