CHAPTER II 

 MATTER 



Proficiency in all of the different divisions of zoology cannot be 

 attained without considerable knowledge of physics and chemistry, 

 though the different fields differ greatly in the demands they make upon 

 such knowledge. An adequate grasp of even the most general and most 

 fundamental zoological principles, however, requires a famiharity with 

 the broad conceptions which underlie those sciences; and since many 

 approach this subject lacking such acquaintance, it is necessary to review 

 briefly these conceptions. Logically, the first subject to be considered 

 is the nature of hving matter. To understand this it becomes necessary 

 to define what is meant by matter in general and to state some facts in 

 regard to it. 



11. Definitions. — Matter has been defined as that which occupies 

 space. We commonly refer to all of our experiences as either material 

 or spiritual. Those which are material presume the existence of matter; 

 those which we term spiritual have no essential relation to it. 



12. Constitution of Matter. — Matter differs in kind, exists in various 

 forms, and exhibits a great variety of phenomena. The study of matter 

 with respect to kind is in the field of chemistry; that of matter without 

 regard to kind, including the phenomena of matter in general, belongs to 

 physics. 



A few common forms of matter consist of only one kind of matter, 

 such as a mass of gold, silver, iron, the Kquid mercury, and the gases, 

 nitrogen and oxygen, in the atmosphere. Most matter with which we 

 are familiar does not consist simply of one kind of matter but is of the 

 nature of a compourid, consisting of two or more different kinds. A 

 piece of any ordinary compound substance, as, for instance, a piece of 

 chalk, is termed a mass and may by being broken into two parts be 

 divided into two masses. These may be again broken, and the process 

 may be continued, resulting in masses of smaller and smaller size, each 

 still remaining chalk. This division may be carried beyond the Hmit 

 of visibiUty by the unaided eye and even far beyond that by the micro- 

 scope. The masses become smaller and smaller, but each bit remains a 

 mass. Finally a fragment may be conceived that can no longer be 

 broken and the portions be ahke. This smallest particle of any com- 



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