476 MINNA E. JEWELL 



centrations of NaHCOs until a 0.006 mol. solution (120 cc. 0.01 

 mol. NaHCOs in 200 cc), is reached. 



In the dilutions used (0.00075 to 0.00225 mol. NaaCOg and 

 0.00075 to 0.006 mol. NaHCOs) the degree of ionization of the 

 salts would be very great, since ionization becomes complete 

 as dilution becomes infinite. If we assume complete ionization, 

 the number of Na ions would be the same in a given solution of 

 Na2C03 as in a solution containing twice as many molecules of 

 NaHCOs, while the osmotic pressure of equimolecular solutions 

 of the two salts would be the same. If, then, the effect on regen- 

 eration is due to Na ions, the same retardation should be produced 

 by 45 cc. Na2C03, 30 cc. each NaaCOa and NaHCOs, or 90 cc. 

 NaHCOs. An examination of figure 5 shows this is not the case, 

 and that it would, in fact, be necessary to assume twice as great 

 ionization for Na2C03 as for NaHCOs in order to explain the 

 physiological effects in terms of the Na ions. Considering the 

 dilution, so great a difference in ionization is highly improbable. 

 On the other hand, it is impossible to attribute the results ob- 

 tained to osmotic pressure, for even if the Na2C03 is assumed to 

 be completely ionized, and the NaHC03 completely undissociated, 

 the effect of Na2C03 would still be proportionately too great, as 

 the depression of regeneration caused by 30 cc. Na2C03is consider- 

 able, while 90 cc. NaHCOs produces no appreciable effect. In 

 view of these facts, and in view of the further fact that the weakest 

 solutions used in these experiments are comparable as to osmotic 

 pressure and number of metallic ions to the strongest solutions 

 of hydroxides employed, it is safe to assume that the important 

 factor in the retardation of growth produced by the metallic 

 hydroxides is the OH ion. 



Carbon-dioxide production and regeneration in bases 



As basic media are generally known to increase oxygen metab- 

 olism, it was thought desirable to try a few experiments to see 

 whether the decrease in regeneration could in any way be corre- 

 lated with the increase in carbon-dioxide production. The 

 methods employed have already been described p. 469). 



