WATEK RELATIONS OF OTHER SPECIES 



141 



empirically ascertained parameter termed "non-solvent volume." 

 By this device the lines A, A', B, and B' actually become straight ; 

 strong suppositions may thereupon be formulated for identifying 

 the rates of water exchanges with forces ordinarily termed osmotic 

 pressures. Often, the "permeability coefficient" h is regarded as 

 having some inseparable and indispensable significance in such 

 study of water exchanges, but I find additional comparisons among 

 diverse conditions and species to be also useful. 





LU 



J 



cn 



Water Load 

 Fig. 87. Initial rate of net water exchange (% of BoAour) in relation to initial 

 water load (Phascoloso^na) . For each point, 5 individuals (0.8 to 2.8 grams each) are 

 transferred at zero time from varying concentrations of sea water to normal sea water. 

 AA', exchange in first 0.25 hour x 4; BB', exchange in first 1.0 hour. The curves are 

 drawn so that the ordinates (within each of the two segments) are proportional to the 

 initial difference of total concentrations between worm and new medium. Additional 

 data of Adolph ('36b). 



Phascolosoma adjusts its water content without, so far as as- 

 certained, the use of processes that are known to require internal 

 energy. The equilibration diagram is nevertheless similar to others 

 that have been studied; it has only two lines instead of the four 

 usually recorded, since it represents only net exchanges. No turn- 

 over has been recognized, unless it be by kinetic interchange of 

 water molecules. Corresponding to the absence of turnover is the 

 small variability of water content (see table 12). The conclusion 

 may not be drawn that all marine animals adjust their water con- 



