596 GEOLOGICAL HISTORY. 



(4.) It was a system of progressive cephalization in the Animal 

 structure ; and in this also it was parallel with embryonic development. 

 Several of the facts already stated (p. 595) illustrate this. The head of 

 an animal is always the part last perfected. In most Insects, even 

 the highest, the young is a worm-like larve, with its several segments 

 much alike in kind and functions ; and the abdomen often serves for 

 locomotion ; but, in the adult, among the higher tribes, the abdomen 

 and thorax have become distinct and greatly contracted ; the abdomen 

 has lost any locomotive appendages it had ; and the head has become 

 a well defined organ, of improved structure and better senses. At the 

 same time, the thorax bears the only locomotive organs. Thus the ab- 

 domen has lost in forces, and the thorax and head have gained ; and 

 so the forces of the animal are in its development thrown toward the 

 anterior extremity, and the structure is thereby cephalized. Now, in 

 the history of the animal kingdom, the many-jointed Worms, with 

 segments almost all alike, preceded the Insects, the higher and more 

 cephalized forms of Articulates. 



This principle might be extensively illustrated; for, throughout 

 the animal kindom, wherever there has been progress, this progress 

 has been attended with advance in stage of cephalization. Advance 

 in cephalization necessarily involves corresponding improvements in 

 structure. 



Animals, high and low, are in contact with the outer world through 

 their nervous system, and eminently by means of the cephalic ganglion 

 (the brain in Vertebrates) ; and it is natural, therefore, that progress 

 and cephalization should have gone forward together, the former in- 

 volved in the latter. 



In Man's structure, we see the last limit to which the law of cephal- 

 ization can carry the system of life. The distinction is well illustrated 

 in the grades of men. The retreating forehead, long occiput, project- 

 ing jaws, and longer fore-arm of the negro, are all marks of inferior 

 cephalization. Progress in the race straightens up the forehead, and 

 shortens in the jaws ; and the abbreviation of the fore-arm also is a 

 consequence of headward concentration in the forces of the system. 

 Degradation is attended with a corresponding decephalization. 



The idea of system in all structure, and of progress through the ages, under laws of 

 specialization and cephalization, according to a scheme that may be compared to the 

 opening of a flower, or the development of a germ, instead of being atheistic, is the 

 only view of the history of life that is consistent with its Divine origin. Were there 

 no such order of succession, no such unity of law and structure, this would be complete 

 demonstration that a Being of infinite wisdom had not ordered or controlled events. 

 Moreover, a Divinely appointed scheme of progress should exhibit, not merely system, 

 but an exact reference to the external surroundings of the species, through the succes- 

 sive changes in the earth's physical history; and so completely, that the succession 

 of life should be the same, whether carried forward by a system of natural causes 

 under a Divine law established at the beginning, or by successive Divine acts. 



