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 familiarity 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 living 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. 



10. Definitions. — For our purpose matter may be defined as all in 

 this universe, of the existence of which we may be made aware through our 

 senses, either directly, or indirectly by means of any kind of apparatus. 

 This will include all that is revealed by the microscope, telescope, spectro- 

 scope, or any other type of instrument. 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. 



11. 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. 



Most matter with which we are familiar does not consist simply of 

 one kind of matter but is of the nature of a compound, 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 limit of visibility by the unaided eye and even far beyond 

 that by the microscope. 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 alike. This smallest particle 

 of any compound substance is termed a molecule. When molecules are 



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