time: the refreshing river 



less as to be with difficulty distinguished from the water it floats in, 

 is not more like its medium in chemical, mechanical, optical, and 

 thermal properties, than it is in the passivity with which it submits 

 to all the influences and actions brought to bear upon it; while the 

 mammal does not more widely differ from inanimate things in these 

 properties, than it does in the activity with which it meets surrounding 

 changes by compensating changes in itself.'* When in just twenty 

 years' time we celebrate the centenary of Spencer's first formulation 

 of this rule of increasing independence,^ we shall be able to look back 

 upon a vast structure of knowledge in comparative biochemistry 

 and physiology which in many directions (e.g. osmotic regulation,^ 

 thermal regulation,^ constancy of the internal medium,* respiratory 

 pigments,^ laws of nitrogen excretion,^ etc.) has verified the synthetic 

 philosopher's insight. 



Nor was this much less remarkable in matters of embryology. 

 His treatment of animal development as a passage from instability to 

 stability has been profoundly justified in modern experimental em- 

 bryology, in which the restriction of potentialities which goes on 

 under the influence of the hierarchy of organiser-hormones bears him 

 out.'^ Already before 1898 he had clearly enunciated the process we 

 know now as ''self-differentiation" under the name "autogenous 

 development."^ Even the organisation-centre, with its primary 

 organiser-hormone, not discovered till 1924, he had adumbrated 

 thirty years earlier, in the guise of an analogy with a party of colonists 

 in new country, which forms for itself an organisation of "butty" or 

 "boss" and those who work under his directions.^ 



But Spencer's treatment of sociological problems is of most interest 

 for the present analysis. He has the great merit of having been among 

 the first thinkers to apply evolutionary concepts to sociology, and 

 for this we owe him a great debt.^^ Nevertheless we meet continually 

 with the paradox that, having spoken so convincingly of the progres- 

 sive integration of systems into ever higher levels of organisation, he 



^ It was first formulated in a review "Transcendental Physiology" in the Westminster 

 Review in 1857 (A, I, 503). Whether his contemporary, Claude Bernard, who developed 

 the concept oi fixite du milieu interieur had any hand in it, we do not know. 



^ See E. Baldwin, Comparative Biochemistry (Cambridge, 1937). 



^ See A. S. Pearse & F. G. Hall, Homoiothermism (New York, 1928). 



* See J. Barcroft, The Architecture of Physiological Function (Cambridge, 1934). 



^ See A. C. Redfield, Quart. Rev. Biol., 1933,8, 31. 



^ See J. Needham, Chemical Embryology (Cambridge, 193 1). 



' FP, pp. 382 ff; see C. H. Waddington, Organisers and Genes (Cambridge, 1940). 



^ PB, I. 365. 9 PB, I. 367. i« PS, I. 617. 



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