DEFECTS OF CURRENT PHYSIOLOGY 91 



various physiological processes can be taught. 

 If, for instance, we are teaching the physi 

 ology of the kidneys, we must teach the main 

 facts bearing on the possible mechanism of 

 secretion of urine. We must thus discuss 

 the possible influence of filtration, diffusion, 

 etc., in the process, leaving out of account 

 all details which are irrelevant to this dis 

 cussion ; and when at the end it turns out 

 that the essential mechanism of secretion is 

 quite unknown there is nothing further to 

 do than pass on to the next subject. Actually 

 it is known that, mechanism or no mechanism, 

 the kidney fulfils its functions of regulating 

 the composition of the blood, and that it 

 does so with marvellous delicacy ; but facts 

 relating to this do not fit into the plan of 

 exposition of the subject, and have too much 

 of a smack of old-fashioned teleology about 

 them. Hence they are ignored completely, 

 or scarcely touched upon. 



It is the same with circulation, respiration, 

 and every other part of physiological know 

 ledge. The fact that the body lives as a 

 whole, each organ or part fulfilling its proper 

 functions and adapting itself to every change, 



