THE DEEPENING OF PHYSIOLOGY. 295 



multiplicity of function, even in organs so familiar 

 as the liver and the pancreas. 



(3) Fuller Recognition of Correlation. For ages 

 men have been familiar with the general idea of the 

 unity of the organism. There are many members, 

 but there is one body ; if one member suffer, the others 

 suffer with it. At the beginning of the century 

 (1805), Xavier Bichat recognised that "each func- 

 tion is linked to all the rest," and the same fact was 

 behind the "balance of organs" of which Etienne 

 Geoffroy St. Hilaire often spoke, and the " division 

 of labour " on which Henri Milne-Edwards insisted. 



As long as we keep to a general view, the facts 

 seem clear enough. That certain organs should be 

 mutually dependent follows from their nature; 

 muscles are dependent on the nerves which stimulate 

 them and the blood vessels which bring them food; 

 the health of the brain or of any other part is affected 

 by that of the liver whose fundamental function it 

 is to be a food-filter and to keep the composition of 

 the blood approximately constant. Facts like these 

 are necessary consequences of the way in which the 

 organism is made. 



We get nearer a realisation of what correlation 

 means, perhaps, when we notice the facts of func- 

 tional compensation. If one lung or one kidney go 

 out of gear the other may do double duty ; if a thyroid 

 gland be extirpated an accessory thyroid body may 

 begin to take its place, and grow large in so doing; 

 if a lobe of a kidney or liver has to be removed there 

 may be a compensatory increase of function in the 

 remainder. 



But let us briefly refer to some less familiar facts 

 which bring out more clearly the intimate correlation 

 which makes the whole body one. 



