GROWTH. 145 



times, as in the weazel, smallness i3 a cor^dition to successful 

 pursuit of the animals preyed upon; and that in some cases, 

 the advantage of resembling certain other creatures, and so 

 deceiving enemies or prey, becomes an indirect cause of re- 

 stricted size. But the present purpose is simply to set down 

 those most general relations between growth and other or- 

 ganic traits, which induction leads us to. Having done this, 

 let us go on to inquire whether these general relations can 

 be deductively established. 



§ 44. That there must exist a certain dependence of 

 growth on organization, may be shown a 'priori. When we 

 consider the phenomena of Life, either by themselves or in 

 their relations to surrounding phenomena, we see that, other 

 things equal, the larger the aggregate the greater is the need- 

 ful complexity of structure. 



In plants, even of the highest tj^e, there is a compara- 

 tively small mutual dependence of parts: a gathered flower- 

 bud will unfold and flourish for days if its stem be immersed 

 in water; and a shoot cut off from its parent-tree and stuck 

 in th(f ground will grow. The respective parts having vital 

 activities that are not widely unlike, it is possible for great 

 bulk to be reached without that structural complexity 

 required for combining the actions of parts. Even here, 

 however, we see that for the attainment of great bulk there 

 requires such a degree of organization as shall co-ordinate 

 the functions of roots and branches — we see that such a size 

 as is reached by trees, is not possible without a vascular 

 system enabling the remote organs to utilize each other's 

 products. And we see that such a co-existence of large 

 growth with comparatively low organization as occurs- in 

 some of the marine Algce, occurs where the conditions of 

 existence do not necessitate any considerable mutual depen- 

 dence of parts — where the near approach of the plant to its 

 medium in specific gravity precludes the need of a well- 

 developed stem, and where all the materials of growth being 



