TIME AND CHANGE 



is t^T)ical of the course of the creative energy from 

 the first unicellular life up to man, each succeeding 

 stage flowing out of, and necessitated by, the pre- 

 ceding stage. 



How slowly and surely the circulatory system 

 improved! From the cold-blooded animal to the 

 warm-blooded is a great advance. In the warm- 

 blooded is developed the capacity to maintain a 

 fixed temperature while that of the surrounding 

 medium changes. The brain and nervous system dis- 

 play the same progressive ascent from the brainless 

 acrania, up through the fishes, batrachia, reptiles, 

 and birds to the top in mammals. The same with the 

 skeletons in the invertebrates, from membrane to 

 cartilage, from cartilage to bone, so that the primi- 

 tive cartilage remaining in any part of the skeleton 

 is considered a mark of inferiority. 



According to Cope, there has been progressive 

 improvement in the mechanism of the body — it 

 has become a better and better machine. The sus- 

 pension of the lower jaw, so as to bring the teeth 

 nearer the power, — the masseter and related mus- 

 cles, — was a slow evolution and a great advance. 

 The fin is more primitive than the limb; the limbs 

 themselves display a constantly increasing differen- 

 tiation of parts from the batrachian to the mamma- 

 Han. There was no good ankle joint in early Eocene 

 times. The model ankle joint is a tongue and groove 

 arrangement, and this is a later evolution. In Eo- 



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