GROWTH. 117 



tures, and so deceiving enemies or prey, becomes an indirect 

 cause of restricted size. But the present purpose is simply 

 to set down those most general relations between growth and 

 other organic phenomena, 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 wo 

 consider the phenomena of Life, either by themselves or in 

 their relations to surrounding phenomena, we see that, other 

 things equal, tho larger the aggregate the greater is the 

 needful complexity of structure. 



In plants, even of the highest type, there is a com- 

 paratively 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 the ground, will grow. The respective parts 

 having vital activities that are not widely unlike, it is pos- 

 sible 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 an efficient vascular system enabling the remote 

 organs to utilize each other's products. And we see that 

 such a co- existence of large growth with low organization, 

 as occurs in some of the marine Algce, occurs where the 

 conditions of existence do not necessitate any considerable 

 mutual dependence 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 derived from the water by each portion of the thallus, 

 there requires no apparatus for transferring materials from 

 part to part. Among animals which, with but few 



