LECTURE XXIX. 

 DEGENERATION. 



Meaning of high and low in biology. 



High may mean : complexity of structure in gen- 

 eral ; complexity of special structure ; complexity of 

 nervous organization ; adaptation to complex environ- 

 ment. 



Man the highest animal through complexity of nerv- 

 ous system and derived powers of will, self-activity, 

 cooperation, speech, and abstract reasoning. All the 

 product of emphasis laid on living by his wits. But 

 specialization of one or many parts implies deteriora- 

 tion in others, as the ape-like strength and spryness 

 are little needed by man. Degeneration of single 

 organs as their highest functions become useless. A 

 law of Evolution. Example : pineal eye ; jaw and jaw 

 muscles ; gills in mammals and birds. Strength in 

 simplicity ; in government ; in education ; in lan- 

 guage. 



Degeneration is decline in rank. Takes place when- 

 ever the struggle for existence permits life on a lower 

 plane of activity or of adaptation. 



1. May take the form of adaptation to less complex 

 surroundings, as in the seal, or blind fish. Then ac- 

 companied by specialization in minor structures. 



2. Reduction of vigor. Preliminary to extinction. 



3. Simple divergence, from isolation and narrowed 

 range. 



