816 Dynamic Theory. 



shows how the slow modification of ancient habits have slowly modified 

 the ancient organic forms. How different degrees and qualities of ac- 

 tivity between the two sides of the body have conferred dexterity upon 

 one side at expense of the other, how the periodicity of the molar 

 movements of the universe have entailed a corresponding periodicity on 

 organic habits, which has in turn been reflected on habitual organic 

 forms, how varying habits of respiration have begotten varying forms 

 of respiratory apparatus, and how, in the cases of animal and vegetable 

 parasitism, the disuse of functions and habits is followed by the sup- 

 pression of their characteristic organs. 



It is to habit, therefore, the habit of function or movement that we 

 must attribute the creation and modification of organs. This is con- 

 spicuously obvious from the numerous illustrations that have been 

 given, and from the numerous other illustrations that cannot have failed 

 to come under the observation of everyone. This induction implies 

 that the function exists before the organ. It may be asked how a func- 

 tion can be performed before an organ for its performance has been 

 created. The answer will be plain enough when we shall have con- 

 sidered the bottom facts and ultimate nature of differentiation and 

 habit. As already often observed, the habit of the organism depends 

 on the impulses of its environment. Some of our illustrations conspic- 

 uously point this out. Such is the case in "periodicity," in which the 

 movements of the solar universe entail corresponding effects in the hab- 

 its of all organic beings. The degree of saltness or freshness in water 

 has its effect on the organisms within its influence. The force of cur- 

 rents of water and air has its effect in first causing new uses to be at- 

 tached to old organs of locomotion, and, second, by this means of new 

 habits, creating modifications of the organs. Endless argument might 

 be brought to prove that the organism is made by its environment. To 

 maintain otherwise is to hold that the organism is originally self exis- 

 tent, that something may spring from nothing, that the organic being 

 may create something from nothing, and give more than it receives. 

 This cannot be. Whatever force or energy an organism manifests, 

 must have been loaned to it from a source outside of itself. 



Fortunately, in the matter under consideration, the original cause of 

 organic modification may be traced and located beyond the boundaries 

 of the organic world using the term organic in its accustomed sense, 

 as distinguished from the mineral or inorganic. All the habits of or- 

 ganic bodies, whether vegetable or animal, are traceable directly or in- 

 directly to habits of the motion and affections of matter, which, if not 

 original and innate, were at least anterior to organisms. The constancy 

 and persistency of these habits of motion are essential factors in or- 

 ganic evolution, for without such persistency the work of one age would 



