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PRINCIPLES OF BIOLOGY. 
THE PBINCIPLES OF BIOLOGY. 
BY HERBERT SPENCER. 
EXPOSITION OF CHAPTER VII., PART I., 
AND 
CHAPTER I., PART II. 
BY W. GREATHEED. 
Chapter 7, Part I. — “ The Sco})e of Biology .” 
Having ascertained in prior chapters that organic matter 
is that matter which is specially sensitive to surrounding 
agencies, that its very unstable compounds in becoming 
stable give out motion, and that the changes of which life is 
made up are internal adjustments to balance outer changes, 
we come to the question how the science of life, usually called 
Biology, shall be mapped out. Mr. Spencer indicates such a 
map, chiefly useful for future application, because much of 
the territory is inadequately explored. We may study (1) 
structure, or (2) function, or (3) the interactions of structure 
and function; and each of these three subjects may be studied 
with special reference to («) the race or ( h ) the individual. 
We have also to study (4) genesis, or the production of succes¬ 
sive individuals. 
The study of structure includes morphology (form study) 
and embryology (egg study), whilst the study of function 
includes physiology and psychology. The study of the 
interactions of structure and function is illustrated by such 
works as Mr. Darwin’s “ Origin of Species.” And under 
Genesis we may study Sexual and Asexual multiplication. 
Chapter 1, Part II. — “ Growth .” 
Growth is the assimilation of similar atoms, and 
may be either organic or inorganic. The wick of an 
unsnuffed candle, or a geological deposit, illustrate the 
latter kind. Limits to growth are almost peculiar to 
the organic kingdom; not quite, however, since the 
growth of crystals has limits. The conditions of 
growth are numerous. The more complex the structure 
or the greater amount of fit food procurable, or the 
more economy in expenditure of force, the greater the pro¬ 
bable size of the animal. Again, the initial bulk of the egg 
or of the embryo, and the easy supply of food, as in the case 
of the nourishment supplied at the breast by Mammalia, 
affect the question. Not only must there be a sufficient 
