Volume 12 Number 9 



The Plant World 



A Magazine of General Botany 

 SEPTEMBER, 1909 



WHAT IS THE USE OF RESPIRATION? 

 By George J. Peirce. 

 Business men realize that the degree of economy of time, 

 energy, and material in the conduct of a business is often the 

 factor which determines profit or loss. In almost all cases it 

 determines the degree of either; in many cases it determines the 

 one or the other. Increased economy implies proportionally 

 increased efficiency. Increased efficiency implies increased pro- 

 duction and increased success. Waste brings harm or, at best, 

 prevents good. 



Turning from these trite generalities to a still general con- 

 sideration of living organisms, we see that they use material 

 in various ways, building their bodies or liberating energy; that 

 they use energy for doing various kinds of work, manufacturing, 

 digesting, transporting food, moving, growing, reproducing 

 themselves; that the speed with which they do these different 

 kinds of work varies somewhat according to the kind and the 

 individual. A swallow is swifter than a grey-hound, but, in 

 proportion to their sizes, both are slower than a young hay- 

 bacillus. All three absorb their food ready-made; they waste 

 no energy in manufacturing food. But they are not equally 

 active, equally efficient. Why? What are the wastes? One 

 waste is in discarding, as useless, material consisting of complex 

 compounds which it cost much energy to elaborate. The urine 

 and fecal matter of animals, and the by-products of bacteria, 

 contain much valuable material which, as the other organisms 

 living upon these wastes prove, can be used for body-building 

 and for the liberation of energy. In this form of waste bird, 

 beast, and bacillus are alike in quality; whether in quantity or 

 not, I do not pretend to know. 



Again, we may ask whether the material retained in the 

 living body and used to furnish energy for the living thing is 

 used economically? To make the question more definite, is 

 the yield of energy high, and is a fair part of the yield available 



