162 



PHYSIOLOGICAL EEGULATIONS 



placed for recovery in a standard Ringer's solution. Duplicate 

 muscles are analyzed with respect to dry residue, to find what their 

 mean water content might be. Negative loads are imposed by first 

 isolating the muscles (method e), and allowing them to desiccate by 

 evaporation. At zero time they also are placed in samples of the 

 chosen Ringer's solution. 



The tolerance curves (fig. 98) show adjustments toward a com- 

 mon final weight. But the final weight is higher than the initial one, 



0.4 0.6 

 Hours 



Fig. 98. Course of total water load (% of Bo). Isolated thigh of Bana pipiens, 

 at about 21° C. The initial weights (Bo) are those found after dipping once into 

 Einger's solution; later weights are after sojourn in Einger's solution since zero time. 

 The lower three series (8 or 9 thighs each) have been previously desiccated in air, sub- 

 sequent to isolation; the upper two series (15 to 19 muscles each) previously loaded by 

 injecting distilled water into the peritoneal cavity of the living frog. In the latter case 

 the initial load is computed from analyses of 30 duplicate muscles by the relation AE - 

 100 (Do/do -100. Data of Wolf ('40b). 



being in the neighborhood of +9% of Vq. Only muscles having 

 excesses of water greater than + 9% of Vo lose water to Ringer's 

 solution after isolation. Whatever the load, changes occur in the 

 initial 0.2 hour that are independent of the later trends. 



In the form of an equilibration diagram (fig. 99), the same data 

 indicate that the volume toward which recovery aims, as well as the 

 rate of exchange, is modified with time. A shift in final volume of 

 the muscle as compared with its original Vo (upon which the 

 numerical scale is based) follows the isolation as such (Parry, '36). 



