Sec. 4. Atoms 



The words "atom' and "atoms' will be often 

 used in the following pages. Therefore, it is deemed 

 proper to state the nature and properties of an atom, 

 so far as known. It is defined as: "An extremely mi- 

 nute particle of matter ; a hypothetical particle of mat- 

 ter, so minute as to admit of no division ; an ultimate 

 indivisible particle of matter. (Cent. Die. 1, p. 365.) 

 The Encyclopedia Britannica says: "Atom is a body 

 which cannot be cut in two. The Atonic theory is a the- 

 ory of the constitution of bodies, which asserts that they 

 are made up of atoms. (Encyc. Brit. 3, p. 36.) A 

 molecule is the smallest mass of any substance, which 

 is capable of existing in a separate form; that is the 

 smallest part, into which the substance can be divided 

 without destroying its chemical identity. A molecule 

 of any substance is conceived of as made up of two 

 or more atoms. (Cent. Die. 5, p. 3822.) 



In biology a cell is defined, first, as the funda- 

 mental form-element of every organized body. Sec- 

 ondly, as a nucleated, capsulated form element of any 

 structure or tissue; one of the protoplasmic bodies, 

 which build up an animal fabric; a body consisting 

 of cell-substance, cell-wall and cell-nucleus, as bone- 

 cell, etc. (Cent. Die. 1, p. 878.) The body of every 

 animal and plant is made of cells; and each cell is 

 composed of many atoms. 



For a full discussion of "The Atomic Theory,' 



