212 W J MCGEE OUTLINES OF HYDROLOGY 



logic product attests process and not time; for under its undulatory 

 property the predominant agency introduces at least the germs of kinesis 

 and cumulative autonomy, rising so far above inert interrelation as ap- 

 parently to bridge the chasm between the typically physical and the 

 nascently physiological. 



ROLE OF WATER IN THE ONTOSPHERE 



A relatively minute fraction of the terrestrial HgO is withdrawn from 

 the distinctive divisions of the hydrosphere and incorporated in living 

 organisms — that is, accumiilated in what may be denoted the ontospliere ; 

 and in this association its behavior is strikingly parallel to that manifested 

 in running streams. In plants a widely variable but always considerable 

 portion of the organism is made up of water ; the circulation involved in 

 tissue growth is wholly dependent on water moving in a manner meas- 

 urably analogous to stream-flow, carrying material in solution and sus- 

 pension if not in saltation, traversing cells in a manner simulating the 

 alternation between pools and rapids in streams, and partly flowing in. 

 duets so arranged as to suggest river systems with their automatically 

 shaped banks and natural levees — for example, in leaves, in which the 

 dendritic vein systems have become progressively more economical during 

 the ages of phytic growth from catamite and ginkgo through lanceolate 

 and lobate types to the deepty digitate forms of later eons. The source 

 of the power involved in maintaining vegetal circulation is doubtless 

 evaporation from the stomata, coupled with capillarity and osmosis in the 

 vascular system extending from roots to leaves, the pull presumably equal- 

 ized throughout by surface tension; and while the circulation may have 

 little or no effect in maintaining the temperature of the organism, many 

 structures have become so adapted as to permit congelation without injury 

 to those plants and products that survive seasonal changes. In animal 

 bodies the quantity' of water is less variable but generally large, averaging 

 some 75 per cent of the weight of the body in the higher orders ; the office 

 of circulation is extended, so that the liquid is loaded with corpuscles and 

 phagocytes and other particles themselves bearing or being materials of 

 tissue growth and waste, and is typically moved by adaptively developed 

 structures in the undulatory (or pulsatory) way characteristic of stream- 

 flow; while the rate of movement and the capacity for load of the circu- 

 latory fluid are regulated by autonomously evolved structures in such 

 manner as to control (increasingly from lower to higher forms) the tem- 

 perature of the organism independently of exterior conditions, much as 

 the atmospheric vapor regulates the temperature of the planet independ- 

 ently of that of interstellar space. 



I 



