highly significantP = 000
B16BL6 injections, a mean of 227 + 27 surface tumours were seen in 12 pairs of lungs compared with 286 + 31 total tu- mours, corresponding to 113 + 11%. Although in both tumours the total lung counts were higher than the surface counts, linear-regression analyses between them shows highly significant (P = 000 1) correlation coefficients, and analysis of variance between surface and total copnts fails to reveal significant differences (B16F1O, 0-2>P>0-1; B16BL6, P>0 2).