CHAPTER XXXVIII 

 THE EFFICIENCY OF THE ORGANISM 



By E. P. Catiicart, M.l)., D.Sc, LL.D., F.R.S., Rcoius Professor of Physio- 

 logy, University of Glasgow. 



The consideration of the efficiency {i.e. the relation of the con- 

 siunption of energy in the form of fuel to the output of energy 

 in the form of effective work) of man in the production of external 

 work is a question not merely of great physiological but of 

 economic importance, as this factor plays an important role 

 in the assessment of an adequate diet. Physiologically we are 

 concerned with the abstract problem of the conversion of food 

 energy into work — that is, the problem is simply the relation of 

 the increased energy output during the actual performance of 

 muscle work to the energy expenditure of a similar period when 

 no work is being done. In the case of industry, armies, etc., the 

 question is plain enough, but there are many factors both psychic 

 and physical which qualify the answer : in other words, the types 

 of work, the conditions under which it is performed and the 

 personal qualifications of the performer all play an important part 

 in the degree of efficiency with which the work is carried out. 

 Hence it is very essential that the " net or jjhysiological " efficiency 

 be differentiated from the " gross, crude, or industrial " efficiency. 

 The " net " efficiency may be defined as the value obtained by 

 dividing the heat equivalent of the external effective muscular 

 work by the increase in energy output of the body developed as 

 the result of the work done. The "gross " efficiency, on the 



TABLE LXXXVII 



495 



