THE RHYTHM OF MOTION. 271 



several movements slacken. So that in the course of the 

 twenty-four hours, those small undulations of which the 

 different kinds of organic action are constituted, undergo 

 one long wave of increase and decrease, complicated with 

 several minor waves. Experiments have shown 



that there are still slower rises and falls of functional ac- 

 tivity. Waste and assimilation are not balanced by every 

 meal, but one or other maintains for some time a slight ex- 

 cess ; so that a person in ordinary health is found to undergo 

 an increase and decrease of weight during recurring inter- 

 vals of tolerable equality. Besides these regular periods 

 there are still longer and comparatively irregular ones; 

 namely, those alternations of greater and less vigour, which 

 even healthy people experience. So inevitable are these 

 oscillations that even men in training cannot be kept sta- 

 tionary at their highest power, but when they have reached 

 it begin to retrograde. Further evidence of rhythm 



in the vital movements is furnished by invalids. Sundry 

 disorders are named from the intermittent character of 

 their symptoms. Even where the periodicity is not very 

 marked, it is mostly traceable. Patients rarely if ever get 

 uniformly worse ; and convalescents have usually their days 

 of partial relapse or of less decided advance. 



Aggregates of living creatures illustrate the general 

 truth in other ways. If each species of organism be regarded 

 as a whole, it displays two kinds of rhythm. Life as it ex- 

 ists in all the members of such species, is an extremely 

 complex kind of movement, more or less distinct from the 

 kinds of movement which constitute life in other species. 

 In each individual of the species, this extremely complex 

 kind of movement begins, rises to its climax, declines, and 

 ceases in death. And every successive generation thus ex- 

 hibits a wave of that peculiar activity characterizing the 

 species as a whole. The other form of rhythm is to 



be traced in that variation of number which each tribe of 

 animals and plants is ever undergoing. Throughout the 



