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 amceba, 

 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 



