Szekessy Vilmos (szerk.): A Magyar Természettudományi Múzeum évkönyve 62. (Budapest 1970)

Kováts, D.: Quantitative xylotomic investigations on the xylem of our home ash trees

Fig. 6. Correlation between growth ring width and fibre length. Fraxinus ornus L. (Sopron). — Accessory graph for the co- and counterdecurrence of the tension and pression wood graphs. — r.c. = rate of codecurrence, — lue, = heterogeneity of counterdecurrences measurements, concerning the volume percentage of the medullary rays, I received an inverse ratio, that is, the ratio of the medullary ray percentage is smaller in a wide growth ring, and vice versa. This inverse ratio is quite expressed in trees Fr. 5 and Fr. 9 (Figs. 12, 13), but less conspicuous in research specimens Fr. 32 and Fr. 11/a (Figs. 14, 15), even though the inverse ratio exists also in these cases excepting tree Fr. 15 (Fig. 16) in which a direct proportion seems to exist between growth ring width and the medullary ray percentage. Even apart from this exception, measurements concerning the percentage of the medullary rays are needed from every growth ring to state explicitly the validity of the inverse ratio, yet its existence might be assumed on the general course of the graphs.