234 GENERAL EVOLUTION. 



teaches that the perfection produced by each successive age has 

 not been the source or parent of future perfection. The types 

 which have displayed the most specialized mechanism have either 

 l^assed away, or, undergoing no change, have witnessed the prog- 

 ress and ultimate supremacy of those which were once their infe- 

 riors. This is largely true of animals which have attained great 

 bulk. Like those with perfected weapons, they have ever been 

 superior to the attacks of other animals in their day, and doubt- 

 less led, so long as food abounded, lives of luxurious indolence. 

 With change or diminution of food, such huge beasts would be 

 the first to succumb, and it is a fact that no type of land animals 

 has maintained great size through many geologic changes. It is 

 true that all of the lines of ancestry of the existing higher Mam- 

 malia, as the subdivisions of the Carnivora, Ungulata, and Quad- 

 rumana, which we know in detail, commenced with types of 

 small size and correspondingly little muscular power. 



Some important conclusions may be derived from what has 

 preceded. It seems that evolution has witnessed a continual run- 

 ning down of types to their great specialization or extinction. 

 That many types have arisen in weak and small beginnings, but 

 that the conflict with more powerful forms has developed some 

 qualities in which they sooner or later excelled, and which formed 

 the basis of their future superiority and persistence. That while 

 this has probably been the true cause of the origin of the many 

 admirable mechanical adaptations displayed by animals, it is pre- 

 eminently true of the development of mind. That the reason 

 why progress has reached its limit in the lines of greatest speciali- 

 zation, has probably been the removal of the occasion of its origi- 

 nal cause, i. e., active exercise in the struggle for existence. This 

 explanation is suggested by the remarkable degradation which is 

 witnessed in animals whose mode of life relieves them from the 

 necessity of working for a livelihood, e. g., the parasites and ses- 

 sile animals whose young are free. Some of these creatures, on 

 assuming their parasitic life, lose the semblance of even the order 

 to which their young belong. The j^rimary stages of various 

 plants move actively through the water like the lowest forms of 

 animals, and their sessile adult condition must be looked upon as 

 a degeneration. It is well known that the endeavor to relegate 

 the lowest forms of life to the two kingdoms of animal and vege- 

 table, has been generally abandoned. The great vegetable king- 

 dom probably exhibits a life degraded from more animal-like be- 



