WITH VEGETABLES. 7 



IV. The presence of a stomach is a very general mark 

 by which an animal can be distinguished from a vegetable. 

 But the lowest animals are surrounded by material that 

 they can take as food, as a plant is surrounded by an 

 atmosphere that it can use in like manner. And every part 

 of their body being adapted to absorb and digest, they 

 have no need of a special receptacle for nutrient matter, 

 and accordingly have no stomach. This distinction, then, 

 is not a cardinal one. 



It would be tedious as well as unnecessary to enumerate 

 the chief distinctions between the more highly developed 

 animals and vegetables. They are sufficiently apparent. 

 It is necessary to compare, side by side, the lowest mem- 

 bers of the two kingdoms, in order to understand rightly 

 how faint are the boundaries between them. 



CHAPTER II. 



CHEMICAL COMPOSITION OF THE HUMAN BODY. 



THE following Elementary Substances may be obtained by 

 chemical analysis from the human body : Oxygen, Hydro- 

 gen, Nitrogen, Carbon, Sulphur, Phosphorus, Silicon, 

 Chlorine, Fluorine, Potassium, Sodium, Calcium, Magne- 

 sium, Iron, and, probably as accidental constituents, Man- 

 ganesium, Aluminium, Copper, and Lead. Thus, of the 

 sixty-three or more elements of which all known matter is 

 composed, more than one-fourth are present in the human 

 body. 



Only one or two elements, and in very minute amount, 

 are present in the body unconibined with others; and 

 even these are present much more abundantly in various 

 states of combination. The most simple compounds formed 



