THE NATURE OF THE OVULAR STALK IN POLYGONACEAE AND SOME RELATED FAMILIES.—In the Polygonaceae the ovule in most

difficult. For this reason, the two means of the single experiments have been taken together and two new means calculated and their difference tested for significance both by the 't' and the 'Z' tests. For variance due to treatment 'Z = 1-426 (theoretical '2T for nx = 1 and n^ = 11 is = 1-133, P = o-oi); 'Z' for variance due to different days or occasion = 0-89641 (theoretical 'Z' for i\ = 11 and «j = 11, is = 0-7785, P = o-oi). '*' = 2-2342 (theoretical't' = 2-07, P = 0-05). The differences due to treatment as well as for occasion of experiment are thus both real and significant. We may therefore, conclude from these experiments, based on 195 coleoptiles exposed and 390 test plants, that the first negative phototropic curvature is correlated with differential auxin distribution of the order of 42 per cent, on the dark side and 58 per cent, on the illuminated side. In regard to the question as to whether exposure to light influences the total auxinproduction we find that although the mean totals for controls (viz. 6-11+6-14 = 12-25) i f° r negative curvature experiments (viz. 7-19+5-14 = 12-33) agree very well, it is not safe to draw any conclusion since we have established from the analysis of variance that variance due to occasion is significant; the excellent agreement may, therefore, be quite fortuitous. Only experiments carried out on the same day can decide this point. Data from two such experiments, viz.