23 S LESSONS FROM NATURE. [CHAP. VII. 



accept, that the body of each living animal forms a true 

 unityofeach unity. The opposite notion, entertained by many, is 

 organism. t | iat eac k or g an j sm j s no ^ a true unity, but that each 



organ, each part of an organ, and each physiological unit has 

 its own independent life, one not subordinate to a higher 

 unity ; so that the whole forms a moving equilibrium of 

 groups, of groups, of groups, of groups of parts. This was 

 the view which Schwann s famed &quot; cell theory &quot; favoured a 

 theory once received, especially in Germany, with an en 

 thusiasm like that which has greeted the Darwinian theory, 

 but which is now generally abandoned. Now, a lifeless, moving 

 equilibrium such, e.g., as a fountain with a complex arrange 

 ment of jets is manifestly but the result of an adjustment of 

 active physical powers, continuing for a longer or a shorter 

 period. During its continuance the action of each separate 

 physical force can be distinctly traced in the result ; there is 

 no, even apparent, internal principle of cohesion, still less is 

 there any tendency to reproduction. Every living being, on 

 the other hand, has manifestly a tendency to undergo a de 

 finite cycle of changes when exposed to certain fixed condi 

 tions, such cycle ending with the reappearance of that form 

 with which it started ; an egg thus ultimately resulting in 

 the production of another egg, and a seed of another seed. 

 Moreover, in each organism the various parts are reciprocally 

 ends and means. 



Instead, then, of considering an animal as a congeries of 

 groups of groups of independently living units, it seems to me 

 more accordant with reason to consider it as one living whole, 

 in the life of which each part, in its degree, participates. 

 Thus the whole organism forms one continuum. For our 

 convenience as anatomists we actually separate it into parts 

 in various ways, and we consider it as made up of such parts ; 

 but, in fact, it is not really made up of parts at all, but is one 

 whole, locally differentiated in various ways and in varying 

 degrees. To illustrate my meaning we may recall the fact 

 that the air-vessels of plants (like the trachea of insects) were 

 once said to be kept open by means of a spiral filament within 



