386 



axes, developed from a goitre-like gnarl-knot. At the places where the pith 

 bridge in the branch node otherwise leads to the bud, either no meristematic 

 layer was found or it remained covered by a bark cap and developed into 

 a small gnarl spike. Instead of the apical bud, I found accumulations of 

 spike primordia which, in the following year, became actual goitre gnarls 

 from which sprouted weak, leafy branches, as in Acer and Tilia. 



So far as may be concluded from their description, the remarkable 

 "cylindrical gnarls" (chichi, nipple) on Gingko Biloba may also be in- 

 cluded under the goitre gnarls. According to Kenjiro Fujii^ these chichi 

 or nipples are found to be cylindrical or spherical excrescences which, as a 

 rule, grow down perpendicularly from older branches. Their size varies 

 from the length of a finger to 2 meters, with a thickness of 30 cm. They 

 resemble normal branches, on which all foliage is lacking. Having reached 

 the soil, they strike root and then are able to develop leaves. Similar for- 

 mations are said to occur on the roots. 



I have given a more thorough description to this form of the goitre 

 gnarl formation, in which normal embryonic buds do not participate, be- 

 cause it demonstrates the importance of the medullary ray tissue in a way 

 which, as yet. has not received the slightest consideration. Frank- cites 

 references, deserving attention, and also describes earlier observations on 

 gnarl structures. In this, however, the chief concern is the explanation 

 of the wavy course of the wood fibres in gnarled wood. We lay the chief 

 weight on the causes, which lead to the broadening of the medullary rays. 

 The form of goitre gnarl, last described, is only the extreme of a tendency 

 to an excrescence of the medullary rays, which may lead to certain canker 

 swellings. In them, however, processes are involved which are caused by 

 wounds, while here we can ascertain internal disturbances in the equilibrium 

 of the processes of growth, but no external ones. 



We are concerned with local increases of pressure and turgor con- 

 ditions brought about by the form of nutrition. Kny's^ investigations in this 

 connection, give us the desired proof. He found, in the action of mechani- 

 cal pressure, that, in the meristematic cells of the medullary rays, the di- 

 vision walls take a different direction and produce two-rowed medullary 

 rays. In this instance, the results of mechanical pressure from outside, 

 must, according to our conception of the matter, be affected also by the 

 mutual pressure of the tissues upon one another, caused by increase in 

 turgor. Since, however, turgor, — a sufficient water supply being pre- 

 supposed, — depends on the constitution of the cell contents, on the abundant 

 presence of compounds which attract water, each increased supply of plastic 

 food xnaterial will give rise to an increase in turgor and a change of the 

 existing pressure conditions in the different tissue forms. 



1 Kenjiro Fujii, On tho nature and orig-in of so-called "chichi" (nipple) of 

 Gingko biloba. Bot. Magazine. Vol. TX. No. 105. 



2 Frank, A. B., Die Krankheiten der Pflanzen. 2d ed., Part 1, p. 82. 



3 Kny, L... iiher den Einfluss von Druck und Zug usw. Pringsheim.s .Jahrb. 

 f. wiss. Bot. 1901. Vol. XXXVII, p. 55. 



