LATITUDE AND VERTEBR&. 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 = come connected with it or subordinated 
euenen to it. Still her is the reducti d 
compe Hea o it. Still another is the reduction an 
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. 
In the cities in general, the conditions 
of individual existence for the man are 
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. 
Analogy of the 
tropical waters 
to cities of men. 
