DOES ACQUIRED VIGOR COUNT? 265 
by the amount of carbon dioxide given off, or by the 
heat evolved, the mere fact that there is equality 
in the amount of metabolism per day or per hour 
in a number of creatures does not seem to tell us 
much. We wish to know the nature of the meta- 
bolism in each case, for it is not a matter of indiffer- 
ence whether the metabolism is mainly concerned 
with proteids or with carbohydrates. Once again, 
a given animal, such as a midge, might have intense 
metabolism for one glorious hour of crowded life 
and a sluggish metabolism for twenty-three hours, 
and yet have its total metabolism for the day equal 
to that of another creature, such as an ameba, 
which had a constant slow-going metabolism all 
the time. It is open to Mr. Bonhote or any one 
else to call “the rate of metabolism” by the name 
“vigor,” but we do not think it means very much 
unless the nature of the metabolism be defined. 
It is not “the pace”’ merely that matters, but the 
direction of the steps. How much of the metabolism 
is anabolic and how much is katabolic; how much 
is adding to the working capital of living matter 
and how much is an accumulation of reserve stock 
that cannot be realized except under particular 
conditions? These and many similar questions 
must be faced before we can consent to call the 
rate of metabolism vigor. 
The author of Vigor and Heredity has been 
observing animals all his life and making breeding 
experiments with rats and mice, cats and dogs, 
pigeons and poultry for fifteen years, and he has 
