260 SYMBIOGENESIS 



G. FUNCTION. 



In this chapter Spencer recognises that the leaves and sap 

 vessels in a tree, and those organs which in an animal similarly 

 carry on nutrition and circulation, as well as those which in 

 the animal generate and direct muscular motion, must be con- 

 sidered as dynamical in their actions, and he speaks of the 

 "accumulation of force" as latent in food and the "transfer 

 of force" as latent in the prepared nutriment or blood. 



These dynamic conceptions are similar to those for which 

 I have so far pleaded. As soon as the bio-economic importance 

 of nutrition is realised, the further step to more accurate bio- 

 dynamic conceptions follows naturally and necessarily. 



He also tells us that physiology, in its concrete inter- 

 relations, recognises special functions as the ends of special 

 organs : the teeth as having the office of mastication ; the heart 

 as an apparatus to propel blood ; this gland as fitted to produce 

 one requisite secretion, and that to produce another; each 

 muscle as the agent of a particular motion ; each nerve as the 

 vehicle of a special sensation or a special motor impulse. It 

 follows that the study of the economic, i.e., co-operative inter- 

 actions and inter-relations of organs and organisms should be 

 certainly within the province of physiology, and indeed one of 

 its most vital objects. 



" Physiological division of labour," according to Spencer, 

 is a very apt term (coined by Milne-Edwards and adopted with 

 full approval by Darwin). 



Perhaps no metaphor can more truly express the nature of this 

 advance from vital activity in its lowest forms to vital activity in its 

 highest forms. And probably the general reader cannot in any other 

 way obtain so clear a conception of functional development in organisms 

 as he can by tracing out functional development in societies ; noting 

 how there first comes a distinction between the governing class and the 

 governed class; how while in the governing class there slowly grow up 

 such differences of duty as the civil, military and ecclesiastical, there 

 arise in the governed class, fundamentally industrial differences like 

 those between agriculturists and artizans ; and how there is a continual 

 multiplication of such specialised occupations, and specialized shares 

 of each occupation. 



