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CHAPTER X. 
LAWS OF ADAPTATION. 
Laws of Indirect or Potential Adaptation—TIndividual Adaptation.— 
Monstrous or Sudden Adaptation.— Sexual Adaptation.—Laws of Direct 
or Actual Adaptation.— Universal Adaptation.—Cumulative Adaptation. 
—Cumulative Influence of External Conditions of Existence and 
Cumulative Counter-Influence of the Organism.—Free Will.—Use and 
Non-use of Organs.—Practice and Habit.—Correlative Adaptation.— 
Correlation of Development.—Correlation of Organs.—Explanation of 
Indirect or Potential Adaptation by the Correlation of the Sexual 
Organs and of the other parts of the Body.—Divergent Adaptation.— 
Unlimited or Infinite Adaptation. 
In the last chapter we reduced into two groups the phe- 
nomena of Adaptation or Variation, which, in connection 
and interaction with the phenomena of Heredity, produce 
all the endless variety of forms in animals and plants— 
first, the group of indirect or potential, and secondly, the 
group of direct or actual Adaptation. We shall occupy 
ourselves with a closer examination of the different laws 
which we can discover in these two groups of the phe- 
nomena of variation. Let us first take into consideration 
the remarkable and very important, although hitherto 
much neglected, phenomena of indirect variation. 
Indirect or potential adaptation manifests itself, it will be 
remembered, in the striking and exceedingly important fact 
