The current theory of acid-base chemistry regards [H+] as a dependent variable: changes in pH of a fluid can only occur by alteration of strong ion concentrations ([Na+], [K+], [Cl-]). The objective of this study was to determine whether manipulation of sub-embryonic fluid strong ion composition would alter [H+] in the direction predicted by theory. Changes to fluid strong ion concentrations decreased pH in the way predicted and the changes in Cl- suggest a passive distribution. Also, changes in organic anions suggest an essential role for these in acid-base chemistry of this fluid. It was notable that both Na and HCO3- were unaffected by the treatments emphasising the importance of these two ions in fluid production by the quail blastoderm
