13. 

 of animals was involved. The first, seventh, ani fifteenth dishes were dlatillad 

 water octrois. In figures 6, 7 and 3 tin line, or our** of growth of the 

 controls «ae plotted froa the average a of these three. 



If iirotio preasurs is the important factor in the concentrations 

 uael, retardation of regeneration should be the sans, or very nearly the same, 

 in equi-soleoular solutions of Sa^COa and NaHCOa. If the Va-ion Is the 



laportsnt factor, thirty, sirtv, ninety and one hundred twenty c.c. of XaHCX>3 

 should h-.vo epproxlaately tha tacee effects as fifteen, thirty, fourty-five and 

 sixty c.c. of Va2C03 respectively, while thirty c.c. each of tfa^COs and 83HCO3 

 should have the enas effect as forty -five o.c. MajjCOa* 



Tables 5,5a an>* 6 show that this Is not the case. Table 4 and 

 Pig. 5 eho* a progressive and rap 13 deere^ea in regeneration in increasing 

 concentrations of VagCX^. The tadpoles in 60 an J 75 c.c. died ia four and 

 three days respectively without h*.vin: .niorgona any regeneration. Table 5 show* 

 no anrkad decrease in regeneration in increasing concentrations of 9aHC03 until 

 a .006 aol. solution (120 c.c. in 200) Is reached, although the control gives 

 the best regeneration. The low psresntage of regeneration of the tadpoles in 

 30 c.c. oust be attributed to chance as thoao in both the higher and lower 

 concentrations showed better regeneration. 



The curves of regeneration shown in figursa 6, 7 and 3 bring out 

 •ore clearly the difference in effect upon regeneration of fagCOs and WSHO3. 

 Thus while 15 c.c. Sa^COs ani 45 c.c. HaHCOs (Fig. 5) depress regeneration but 

 little more than either of the salts alone, 45 c.c. KA2OO3 and 15 c.c* IfaHX^ 

 (Tig, 3) give practically the easo depression as 45 c.c. fagCOa alone, which Is 

 inooaparably greater than the depression caused by 45 c.c. RoHCOa alone. 



Since there Is this great difference in depreesion of regeneration 

 between equl -molecular eolutlone of th*» carbonate and bicarbonate, and alnce 



