LATITUDE AND VERTEBRAE. 



227 



Another phase is the process of cephalization, the pro- 

 cess by which the head becomes emphasized and the 

 shoulder bones and other structures be- 

 Cephalization QQxcit. connected with it or subordinated 



. . to it. Still another is the reduction and 



competition. 



change of the swim bladder and its utter 

 loss of the function of lung or breathing organ which it 

 occupied in the ganoid ancestors of modern fishes. 



The life of the tropics, so far as fishes are concerned, 

 offers many analogies to the life of cities, viewed from 



the standpoint of human development. 

 Analogy of the ^^ ^j^^ c\\:\^s in general, the conditions 

 tropical waters r j- j , • ^ r ^l 



. . , of individual existence for the man are 



to cities of men. 



most easy, but there also competition of 

 life is most severe. The struggle for existence is not a 

 struggle with the forces and conditions of Nature. It is 

 not a struggle with wild beasts, unbroken forests, or 

 stubborn soil, but a competition between man and man 

 for the opportunity of living. 



It is in the city where the influences which tend to 

 modernization and concentration of the characters of 

 the species go on most rapidly. It is adaptation or 

 death to each individual in the city : every quality not 

 directly useful tends to become lost or atrophied. 



Conversely, it is in the " backwoods," the region 

 farthest from human conflicts, where primitive customs, 

 antiquated peculiarities, and useless traits are longest 

 and most persistently retained. The life of the " back- 

 woods " may be not less active or vigorous, but it will 

 lack specialization. It is from the unused possibilities 

 of the "backwoods" that the progress of the future 

 comes. The high specialization of favoured regions 

 unfits its subjects for life under changed conditions. 

 The loss of muscular power is often one of the results 

 of skeletal specialization. 



