INTRODUCTION 



EVER since the application of theories of evolution 

 to social phenomena, there has been a constant inter- 

 change in terminology between biology and sociology ; 

 societies have been called organisms, and organisms 

 societies of cells. There is an actual division of 

 labour among the organs of a living body, while 

 institutions have been called the organs, or parts 

 of organs, of Society. The interchange of matter 

 effected among the organs of an individual has been 

 called a " physiological contract," while the circula- 

 tion of money may be compared to the circulation 

 of blood and lymph. , Questions arise as to what 

 extent such comparisons are legitimate, if they 

 should be taken in any other than a metaphorical 

 sense, and if it is possible to set a precise boundary 

 between the provinces of biology and sociology. 



Much has already been written on such problems 

 as these, and no doubt much more will yet be 

 written. We shall not attempt either to discuss 

 or to solve them in these few introductory pages ; 

 they are merely touched upon here, and will only 

 be alluded to when absolutely necessary for the 

 careful investigation of facts bearing upon our work. 



I. Societies and organisms. The analogy exist- 



