Herrick, Physiological Problems. 375 



suggestion, the dynamic interpretation of which may be useful. 

 He says: "If then this real immortality is simply a cyclical move- 

 ment conditioned on earlier physical properties of protoplasm, 

 why should it be inconceivable that this property, under certain 

 circumstances, should alter to some extent so that the phases of 

 metabolic activity should not exactly repeat themselves, but after 

 a certain number of cycles should come to an end, resulting in 

 death." As so defined the much-mooted law^ of immortality 

 becomes only the recognition of an equilibrated activity constant 

 only under exactly constant and uniform conditions. But physical 

 conditions are never uniform; yet a vital activity acquires a 

 high degree of egocentric stability by virtue of its activity and is 

 able to resist numerous variations and to return to its regular 

 orbit after mutations. When, however, this disturbance is carried 

 beyond a certain critical angle or degree the equilibrium is 

 destroyed (traumatic death). It is conceivable that in a hostile 

 environment the disturbance might be msufhcient to inhibit the 

 activity at once but nevertheless might introduce an antagonistic 

 element which either becomes cumulative, increasing the diver- 

 gence from the normal in each cycle and so at last pass the critical 

 point or that the change might be insufficient to break up the 

 equilibrium till some nodal point is reached where its effect is for 

 that time adequate. 



The above suggestions point to the necessity of expanding the 

 very limited idea we may secure of the nature of vital activity from 

 the study of structure alone by such a study of function <:s shall 

 note the correspondence, periodicities, incompatibilities, inhibi- 

 tions, nodal points, and the like, and from these create a science 

 descriptive of vital phenomena in terms of modes of energ^■. The 

 locus formula of any given vital activity once secured, we mav hope 

 to extend our knowledge by leaps and bounds. 



