264 SECRETS OF ANIMAL LIFE 
have dwelt on this popular concept of vigor not 
because we are confident we know what vigor 
precisely is, but because we are convinced that it 
means more than is indicated in a recent work of 
considerable interest which bears the title Vigor 
and Heredity.» According to the author, Mr. J. 
Lewis Bonhote, well known as an experienced orni- 
thologist, vigor may be defined as “activity of 
nutrition and function,” or as “ rate of metabolism.” 
It is not so much like heat as like temperature; and 
it requires to be qualified by some adjective, as 
“high vigor,’ or “low vigor.” It is the rate of 
metabolism. Now “metabolism” is just a con- 
venient general term for the manifold complex 
chemical processes which go on in a living body, 
some of them of a constructive, synthetic, upbuild- 
ing, or assimilative character (anabolic), and others 
of a disruptive, analytic, down-breaking or disas- 
similative character (katabolic). But it is a very 
wide term and includes such a variety of processes 
that ‘“‘ the rate of metabolism” does not mean very 
much. Two creatures may have the same number 
of chemical transactions per hour, and yet have 
very little in common from a physiological point of 
view, just as two shops may have the same number 
of sales in a day and yet have very little in common 
commercially, And, again, if we measure the 
amount of metabolism that goes on in a day in 
various types by the amount of oxygen used up, or 
* Vigor and Heredity. By J. Lewis Bonhote. West, New- 
man & Co, 1915. 
