GROWTH. 11 ( J 



implies sucli various structural arrangements as shall make 

 possible these variously-adapted actions. It cannot be 

 questioned that, everything else remaining constant, a more 

 complex animal, capable of adjusting its conduct to a greater 

 number of surrounding contingences, will be the better able 

 to secure food and evade damage, and so to increase bulk. 

 And evidently, without any qualification, we may say that a 

 large animal, living under such complex conditions of exist- 

 ence as everywhere obtain, is not possible without compara- 

 tively high organization. 



While, then, this relation is traversed and obscured by 

 sundry other relations, it cannot but exist. Deductively we 

 see that it must be modified, as inductively we saw that it is 

 modified, by the circumstances amid which each kind of or- 

 ganism is placed ; but that it is always a factor in determin- 

 ing the result. 



§ 45. That growth is, cceteris paribus, dependent on the sup- 

 ply of assimilable matter, is a proposition so continually illus- 

 trated by special experience, as well as so obvious from general 

 experience, that it would scarcely need stating, were it not re- 

 quisite to notice the qualifications with which it must be taken. 



The materials which each organism requires for building 

 itself up, are not of one kind, but of several kinds. As a 

 vehicle for transferring matter through their structures, all 

 organisms require water as well as solid constituents ; and how- 

 ever abundant the solid constituents, there can be no growth 

 in the absence of water. Among the solids supplied, there 

 must be a proportion ranging within certain limits. A 

 plant round which, carbonic acid, water, and ammonia exist 

 in the right quantities, may yet be arrested in its growth by 

 a deficiency of silica. The total absence of lime from its 

 food, may stop the formation of a mammal's skeleton : thus 

 dwarfing, if not eventually destroying, the mammal ; and 

 this, no matter what quantities of other needful colloids and 

 crystalloids are furnished. 



