167 



The "Chichi" (Hippies) of Ginkgo biloba oAe gnarl 

 formations which arise after injury but originate like 

 many bark tubers of the |[eech from definite buds. They 

 are leafless, branch-like excrescences which, on the ' 

 shoots and roots, can grow out into adventitious buds, 

 even becoming H meters long. Keniiro^ calls them "cylin- 

 der-gnarls" on account of their form. The arrangement 

 of their t racheids is irregular, like gnarls. 



4, Wound -> cork. 



After in;}ury of different organs,- roots, tubers, rhi- 

 zomes, stalks, leaves, infloreKcences,~ several layers of 

 cells are often formed arranged in rows, and generally in 

 immediate adjacency to the place of injury. Since the newly 

 produced walls react to known reagents (sulphuric acid, 

 chlor-iodid cf, zink, Sudan III, etc.) as dfco those of cork, 

 sin«« the abnormal tissue corresponds to cork in the arrange- 

 ment of its elements and since further the dependence of its 

 production upon the abnormal conditions created by the injury 

 is unraistakablgr, the products described have for a long time 

 been called wound -cork . 



V/ound-cork is generally formed on all parts of the 

 wound and at its edges connicts directly with the normal mem- 

 brane of the injured plant organs,- epidermis or cork. The 

 new cork formation thus seems to close the wound. Since 

 wound-cork doubtless reduces the transpiration of the exposed 

 tissues and may indeed in other respects be able to compen- 

 sate for the normal meiabrane, we may assume that, by its for- 

 (186) mation, the continuance of the exposed tissues and of their 

 fuijctional activity is assured and we may speak of a heal ing 

 of the wound by the formation of cork. 



There is not much to be said concerning the life-his tory 

 of wound- cork . A number of celldi visions takes place in 

 either one or in more cell layers under the surface of the 

 wound and parallel to it. Hot infrequently an obvious meris- 

 ten zone is thus produced and the wound cork is increased 

 through the activity of its division. The ground tissue is 

 here, as in many other cases, by far the most efficient; the 

 thin-walled, imrenchj/matic parts as well as the collenchjTma 

 fibres are capable of producing wound cork. Besides these, 

 the cambium and the bark produced from it come under consid- 

 eration and finally the epidermis also. If the last becomes 

 active in the formation of wound cork, each cell generally 

 seems to be capable of very few divisions. In bounds oi5 the 

 stems anii leaves, the derivation of the epidermis and of the 

 ground tissue form together a homogeneous wound cork plate, - 

 It is known that the place of production of the normal cork 

 of the trunk (epidermis or ground tissue) is, however, usu- 

 ally constant in genera and families. 



^^® histology , of wound cork is characterized by the ar- 

 rangement m rows of its sheet-like elements, The walls of 

 wound cork are always thin and often folded, I found thin 

 walled wound cork even in Cytisus, the normal cork of whose 

 trunk is known tobe made up of thick walled cells. Differen- 

 tiations of any kine whatever, formations of zones, lenticels 

 and the likk, entirely absent in wound cork. Its cells %re 



i On the nature and origin of so-called "chichi" (nipple) 

 of Ginkgo biloba , Botan. Magaz, 16.06, Vol. IX, au«h Zeitschr, 

 ff. Pfl, Krankh. 1896, Bd. VI, p. 885, 



