Production of Growth Substance by Bacteria in Media Containing Specific Organic and Inorganic Nitrogenous Compounds

THE STRUCTURE OF MYCORRHIZAL ROOTS OF FAGUS SYLVATICA

“…It is often supposed, therefore, that the morphological reaction of the host organ to infection is due to its reaction to substances produced or induced by the infecting organism (Thimann, 1936;Grieve, 1943). The same kind of argument has naturally been used to explain the structural peculiarities of mycorrhizal roots (Burkholder, 1939). The very interesting suggestion has recently come from McComb & Griffith (1946) that hypertrophy of short roots may occur without the formation of a mycorrhiza and that in Pseudotsuga taxifolia the number of such hypertrophied roots increased with the amount of phosphate applied to the soil.…”