871 



alive by these tubers without any growth of the feeding root. As a rule, 

 the piece of root, bearing the tuber, is found to be dead and decaying a few 

 centimeters from the tuber. Andreae^ describes gnarled tubers on the roots 

 of Ailanthus glandulosa; they are produced from roots and from branch 

 primordia. 



In connection with this, a structure may be mentioned here which is 

 often described as the Club root of beets~ but has not yet been sufficiently 

 explained. Usually in dry soil there appears near thd crown, or a little 

 farther down, a spherical swelling covered with cork, resembling the root 

 body in structure but differing from it in composition because of a greater 

 water, ash and protein content. The vascular body shows that the swelling 

 should be considered as the enlargement of a vascular ring of the parent 

 root and may, therefore, be considered an offshoot of it probably caused by 

 an excess of nitrogen after some injury^. The swelling is not parasitic but, 

 because of its porous bark structure and its inert sugar content, is easily 

 infested by animal and vegetable enemies. 



Leaf Injuries. 



In consideration of the fact that the results of injuries appear more 

 clearly in leaves and other fleshy parts of plants, we will call attention to 

 the conditions which w^e call wound stimulus. The first effect of the 

 stimulus, which is exercised on the organ by every injury, may well consist 

 in a traumatropic deposition of protoplasm in the tissue immediately adja- 

 cent to the wound surface. According to Nestler's* investigations, the 

 protoplasm in the uninjured cells collects on the side toward the wound and 

 somewhat later the nucleus moves toward that side. This action of the 

 stimulus extends a few cell rows into the healthy tissue and after about 48 

 hours reaches its maximum. After this, a more or less complete return to 

 the normal condition sets in. This change in position seems to take place 

 more quickly in the light than in the dark. 



In the same way, the chlorophyll apparatus often- undergoes a consid- 

 erable change of position-'^. In many cases an increase of respiration may 

 be noticed at the same time; in the fleshy parts of plants, especially, a rise 

 in temperature could be proved which has been called fever reaction". The 

 production of carbon dioxid in wounded leaves is said to be especially in- 

 creased if they are poor in carbon-hydrates'^. The reactions set in earlier 



1 Andreae, tJber abnorme Wurzelanschwellungen bei Ailanthus glandulosa. 

 Inaugural dissertation. Erlangen 1894. 



2 Briem, H., Strolimer und Stift, Die Wurzelkropfbildung- bei der Zuckerriibe. 

 Osterr. Ungar. Z. f. Zuckerindustrie 1892, Part 2. 



3 Geschwin, Le goitre de la betterave. La sucrerie indigene. Cit. Bot. Centralbl. 

 f. Bakt. II, 1905, p. 486. 



4 Nestler, A., tJber die durch Wundreiz bewirkten Bewegungserscheinungen des 

 Zellkerns und des Protoplasmas. S. Akad. Wien CVII, I, 1898. 



5 Pfeffer, W., Pflanzenphysiologie. 2nd Ed. 1904, Vol. II, p. 819. Here also 

 literature on the action of Wound Stimulus. 



6 Richards, Herbert Maule, The evolution of heat by wounded plants. Annals 

 of Bot. XI; cit. Bot. Jahresber. 1897, p. 99. 



7 Dorofejew, N., Zur Kenntnis der Atmung verletzter Blatter. Ber. d. Deutsch. 

 Bot. Ges. XX, 1902, p. 396. 



