212 Hydrion Differentiation Theory of Geotropism . 
arrangement on the <£ ratio or spiral of Pheidias and the conco¬ 
mitant Fibonacci ratios are the natural consequences. 
As a special case we have the opposite and decussate phyllo- 
taxis (Fig. 3) where the lateral fields are equal in magnitude and 
in shape with the production of two equal, neutral areas arranged 
at right angles to the plane of the first two leaves. As these first 
leaves pass away by the elongation of the axis the primordia 
induced by them develop in their turn two electric fields which 
induce neutral areas and primordia directly above the first pair of 
leaves. These suggestions by analogy are being followed up and 
the results will be published later. 
The Queen’s University of Belfast 
June 16th, 1920. 
REFERENCES. 
1. Kidd, F. Laboratory Experiments on the Sprouting of Potatoes in various 
Gas Mixtures. New Phytologist, XVIII, p. 248, 1919. 
2. Small, J. A Theory of Geotropism. New Phytologist, XIX, p. 49,1920. 
3. Fitting, H. Untersuchungen liber geotropischen Reizvorgange Jahrbuch. 
f. wiss. Botanik, XLI, Teil I, p. 282. 1905. 
4. Newcombe, F. C. Geotropic response at various angles of inclination. 
Ann. Bot. XIX, p. 311, 1905. 
5. Small, J. Changes of Electrical Conductivity under Geotropic Stimulation. 
Proc. Roy. Soc., Lond. B, 90, p. 349, 1918. 
6. Church, A. H. On the Interpretation of Phenomena of Phyllotaxis. 
Oxford Bot. Mem,, No. 6, 1920. 
7. Cook, T. A. The Curves of Life. Constable, London, 1914. 
