72 THE ACTIVE FORCES OF LIVING ORGANISMS 



by massage for a short space of time, yet it is very 

 difficult to produce in this way the continuous yet 

 fairly regular variations which obtain under conditions 

 of health and rapid metabolism. 

 The influ- Nervous action, whatever may be its special features, 

 pre-exi3t- always consists of certain groupings of the excitable 

 ciitioii3. molecules which constitute nervous matter. These 

 groupings may be normal or they may be abnormal 

 and pathological, and in both cases the degree of 

 permanence of the character they possess will depend 

 on the force and duration of the influences to which 

 they are subjected. As bearing on the phenomena of 

 metabolism, it may be said that absolute changes in 

 the mode of vibration of the nerve-cells are very rare, 

 especially in natures which are not hyper-sensitive or 

 excitable. In passing from one set of conditions to 

 another there is always something of the old influence 

 still acting and blending with the new. This is a point 

 which must be borne in mind in estimating the effect 

 of residence at any given altitude, and, above all, in 

 interpreting the results obtained from experiments in 

 the pneumatic chamber. 

 Appiica- No truly systematic theory of the nature of physio- 

 theory of logical processes can be evolved which is not based 

 ethereal to some extent on conceptions of the fundamental 



nature of 



electricity relations of force and matter, or, to use the alternative 



logy. phrase, of matter in motion. In this respect it 



therefore becomes necessary to refer briefly to certain 



possible deductions from the general views already 



expressed. We started, it will be remembered, by 



