Fig. 7. Length (A) and mass-specific length (B) of the AP as a function of pH. The influence of pH was determined in the absence () and presence (•) of added NaCl. (A) Length was significantly influenced by pH in the presence (P<0.005, F=8.24, d.f.=29) but not the absence (P>0.19, F=1.75, d.f.=29) of NaCl. (B) In the presence of NaCl, pH had a highly significant influence on mass-specific length (P<0.0001, F=13.23, d.f.=29). In the absence of NaCl, no influence of pH on mass-specific length was observed (P>0.86, F=0.15, d.f.=29).