VII. Further experiments and histological investigations on intumescences, with some observations on nuclear division in pathological tissues

Abstract

In a paper published in 1900 a description was given of certain pathological outgrowths, first called intumescences by Sorauer, but known as œdemata to American writers, occurring spontaneously on Hibiscus vitifolius , Linn. The paper is mainly anatomical , and the various modifications of intumescences found on the stems and leaves are described. On the stem the outgrowths originate by cell division, which is followed by the elongation of the cells concerned. At a later stage the stem intumescence is cut off by cork, so that the cells above the layer of cork die and collapse. In leaf intumescences there is less cell division and no formation of cork. Preliminary experiments were made to determine the conditions under which intumescences arise, and showed the importance of changes in the external conditions in connection with the question of the formation of outgrowths. Strong and healthy plants, grown in the open air , did not develop intumescences, nor did very weakly plants grown in a cool and poorly lighted, though damp, greenhouse. On the other hand, plants grown in warm, damp, well-lighted greenhouses produced intumescences in varying number and degree.