16 



small-celled bark, rich in ohromatophores, is regenerated from 

 the largQ, colorless or slightly colored cells of the pith. 

 According to Massart-^ some "brown algae (Laminaria, Pelvetia) also 

 "behave in this way; in them a small celled soar-tisstte is also 

 produced from the exposed inner layers, which resembles the bormal 

 bark tissue. 



Only a few cases of tissue restitution are known in the high - 



(19) er plants . The periderm is on the 7/hole easily regenerated, ^the 

 epidermis , however, not always. Although in "physiological" In- 

 juries, by means of vvhich perforated or seci-eted leaves of differ- 

 ent plants obtain their characteristic form, a tissue is formed" 

 at the edge of the wound, which corresponds v^ith the epidermis^, 

 yet when the integrity of the stems and the leaves is violently 

 distrubed generall;?- no new formation of the epidermis takes place. 

 Tittman has proved this definitely by countless experiments. Ac- 

 cording to Massart floe. cit. p. 55) the leaves of Lysimachia 

 vulgaria seemingly form an exception to the rule; they regenerate 

 normal hair -bearing epidermis, when injured in a very young stage. 

 In roots, the ability to form new epidermis after injury is wide- 

 spread; Lopriore* observed on split roots the formation of normal 

 epidermis provided with root hairs, (Compare fig. 4). In the for- 

 mation of lateral roots also a typical epidermis arises from the 

 derivatives of t^e more deeply lying layers of tissue. 



Finally the regeneration of the vascular bundles is to be 

 mentioned. Roots and shoots which have been split lengthwise will 

 complete each helf of the fibro-vascular system to a complete cen- 



(20) tral cylinder?. In monocotyledons, regeneration of roots takes 

 place by the simultaneous restoration of epidermis, phloem and 

 xylem. In dicotyledons, hov/ever, the endodesmis is regenerated! 

 first, later the xylem and phloem (Compare again fig. 4). In the 

 same way, after splitting shoots of Salix, Aristolochia, LonicerQ, 

 Sambucus and many others, Kny observed the production of wound 

 tissue from pith, carobium and bark, in which a new cambium was 

 formed. This wq,s connected on both sides with the cambium of the 

 normal vascular -bundle, and, like this, produced xylem elements 

 towards the inner phloem elements towards the outer side. The 

 investigations of Kny and Lopriore make it prtebable that very 

 many, if not all, phanerogams possess the abilitjr to restore des- 

 troyed central cylinders. 



Massart, La cicatrisation Chez 1, veg, Mem. Cour, et 

 autres.mem. Acad. So. Belgique, 1898. T, L"VII. 



2 



Tittmann, loc, cit, p, 117. 



Schwars, 3?r., fiber die Entstehung der Lochdr and Ein- 

 buchtungen an dem Blatt von Philodendron pertusum. Sitzungsber, 

 Akad. Wissensch. Wien, 1878, Bd. IXXVII, A"^t. 1, p. 367; 

 lippitsch^ Ueber das Einrelssen der Laubblatter der Musaceen 

 and einiger verwandter Pflanzen, Oest. Bot . Zaatschr. > 1889, 

 Bd. 2XXIX, p. 206. 



^ XJber Regeneration gespaltener Wurzeln, loc. cit. Compare 

 also Ber. B. Beutsch. Bot- Ges., 1892, Bd. Z, p. 76. 



Compare especially Kny, Ueber kunstliche Verdoppelung 

 des ieitbundelkreises im Stamrae der Bikotyl. Sitzungsber. Uaturf . 

 Fr. Berlin, 1877, p, 189, Lopriore, loc. cit. and Vorlaufige 

 Mitteilung uber die Regeneration gespaltener Stammspitzen. Ber. 

 der Beutsch, bot. Ges., 1895, Bd, ZIII, p. 410. 



