6 £ETD-3446(App. ) responses induced by 2, 4-2 exe 2. £,. 5-T are very similar to those of a growth substances, except taes “ca#T are more marked in degree. In tom there is stimulated cell prositee=-= and lateral root production, whine2 other cases, there is greater cami-a- activity and the formation of this xylem cells (29). Viruses in plants uscally to not affect the meristematic regions. as continued normal functioning of te meristem of the growing points end¢ regions of most virus-affected piamts indicates that if viruses are pres‘ the meristem they rarely eause azcveciable direct injury to this typeof (2)¢ dn exception to this statenaxt is the virus-produced tumor reported | Kelly and Black (20). This tumor arose chiefly in the pericyclic regionvf and stems and consisted of groups of distorted tracheids surrounded bys tic cells and parenchyze interspersed with phloem. Description of Tumors om Ipomoea ‘ubaThe tunors varieé from smal: wart-like tubercles’‘at'the nodes tohares contorted masses 5-6 ecextiasters in eireuference (Figures 5, and Sb). Tee were yellowish-greex. is eolor, but the leaves produced on the newer cree were normal in colore the tumorous masses themselves, indicating at least partial recoverye : Histology. = Whole tumors were brought to the laboratory in FAA. Pieces of the ta tissue weree dehydrated and cleared in an alcoholechloroform series end in "Tissuemat." They were sectioned serially at l5u and stained by comantll Quadruple stein schedrie. Sections of the stem of normal plants grown tree seed in the greenhouse were fixed in FAA and either stained and sectioned a above or sectioned at Zia on a freezing microtome and stained with satrani fast greene / UNIVERSITY ARCHES UNIV. OF WASH. Libé