lotka: efficiency in organic evolution 401 



uring values of materials to animals have been devised. But 

 there is nothing inherently impossible about the solution of the 

 problem of measuring these values, and, in fact, if it seemed 

 worth while, suggestions could be made at this juncture as to 

 how the first crude steps at any rate in this direction might be 

 taken. 



Furthermore, since an objective standard of value has been 

 furnished in a previous communication, a standard which is 

 quite independent of the subjective estimate of values and which 

 applies with absolute impartiality to any species, there is in 

 principle no difficulty whatever involved in extending our argu- 

 ment from man to other members of the animal kingdom. The 

 difficulties which arise are only those of translating our results 

 into concrete practical examples. 



3. Several restrictions in the scope within which our argu- 

 ments are strictly applicable are introduced through the fact 

 that we have made use of Jevons' equation for the distribution 

 of labor in different pursuits, or its equivalent. The first of the 

 limitations thus introduced is that our arguments strictly apply 

 only to a community in which there is absolutely free competi- 

 tion and no kind of a monopoly. 



In the case of animals this condition is probably in most cases 

 approximately fulfilled. 



In the case of a highly developed industrial community of the 

 human species this assumption is very far from the truth. The 

 case of such a community requires special consideration by more 

 complicated methods, and further work in this direction will 

 have to be done to complete the discussion. The writer hopes 

 that perhaps he may be able to take up this phase of the prob- 

 lem on another occasion. In the meantime the simple case 

 here considered illustrates the principles at work just as well 

 as a more complicated case. 



4. Another limitation introduced by the use of Jevons' equa- 

 tion is the fact that our arguments apply only to a steady state, 

 in which consumption equals production. 



As a matter of fact conditions in nature in all probability 

 approach a steady state in most cases. This is almost inevitable, 

 since a persistent excess of production over consumption would 



