CHAPTER VIII 
ADAPTATIONS 
74. Origin of adaptations—The strife for place in the 
crowd of animals makes it necessary for each one to adjust 
itself to the place it holds. As the individual becomes 
fitted to its condition, so must the species as a whole. The 
species is therefore made up of individuals that are fitted 
or may become fitted for the conditions of life. As the 
stress of existence becomes more severe, the individuals fit 
to continue the species are chosen more closely. This 
choice is the automatic work of the conditions of life, but 
it is none the less effective in its operations, and in the. 
course of centuries it becomes unerring. When conditions 
change, the perfection of adaptation in a species may be 
the cause of its extinction. If the need of a special fitness 
can not be met immediately, the species will disappear. 
For example, the native sheep of England have developed 
a long wool fitted to protect them in a cool, damp climate. 
Such sheep transferred to Cuba died in a short time, leav- 
ing no descendants. The warm fleece, so useful in Eng- 
land, rendered them wholly unfit for survival in the tropics. 
It is one advantage of man, as compared with other forms 
of life, that so many of his adaptations are external to his 
structure, and can be cast aside when necessity arises. 
75. Classification of adaptations.—The various forms of 
adaptations may be roughly divided into five classes, as fol- 
lows: (a) food securing, (2) self-protection, (c) rivalry, (d) 
defense of young, (e) surroundings. 
The few examples which are given under each class, 
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