“…Many of the reagents and methods used by Onslow (1920Onslow ( ,1921Onslow ( , 1931 and Joyet-Lavergne (1935, 1937 and outlined by Boswell and Whiting (1940) were employed to determine the presence of both oxidases and reductases. It is not intended that the material presented here be taken as proof of a causal relationship between oxidases and endodermal maturation; it is my belief, however, and it will be plain in the discussion which follows, that the presence of an oxidase system in endodermal tissues may be a causal factor in endodermal and related suberic depositions.…”