WATER BALANCES AND EXCHANGES 



289 



were among (a) species, individuals, tissues, and cells; (b) types 

 and agents of increment and conditions of recovery; and (c) paths 

 of water exchange. The preferred characterizations were such as 

 were demonstrated to apply to very diverse sorts of living units, 

 almost regardless of their special structures and functions. Less 

 general criteria were available when additional correlatives were 

 taken into consideration. Thus, all organisms exhibit water ex- 

 changes after a water increment is imposed ; but only some exhibit 

 exchange through integumentary paths, or in proportion to exposed 

 area. 



TABLE 32 

 Adjustments of water load. G = gain, L = loss 



Species 



Dog 



Garter snake 



Eat 



Phascolosoma 



Earthworm 



Frog 



Man 



Eabbit 



Arhacia egg (data of 



Lucke) 



Zoothamnium (data of 



Kitehing) 



Net gain in deficit 



Hours for 

 half return 



0.02 



0.04 



0.15 



0.4 



1.0 



1.4 



1.6 



0.04 



0.1 



0.02 



Modifications 



G, (L) 

 G 



G, L 

 G 



G, L 

 G, L 

 G,(L) 

 G, L 



G 



G, L 



Net loss in excess 



Hours for 

 half return 



1.5 

 4.0 

 1.8 

 1.5 

 1.6 

 2.3 

 2.1 

 1.8 



0.04 



0.2 



Modifications 



G, L 

 (G),L 



G, L 

 L 

 L 

 L 



G, L 



G, L 



Within one class of animals showing structural similarities, 

 e.g., vertebrates, water increments are accompanied by character- 

 istic changes in particular tissues. In vertebrates, some of the 

 modifications found are in : 



(4a) Tissue volumes, volumes of distribution; 



(4b) Tissue concentrations ; 



(4c ) Amounts of components in tissue and body ; 



(4d) Pressures within tissues. 



(8a) Rates of exchange of components ; 



(8b) Rates of transformation of energy; 



(8c ) Rates of circulation of blood and other fluids ; 



(8d) Behaviors and other physiological activities ; 



(8e) Responses to excitations, agents. 

 The diverse sorts of modifications in tissues coincident with incre- 

 ment in a single variable (AW) constitute a whole pattern of strains 

 or displacements ; the organism is then out of kilter until recovery 



