(a) When the entire injured organ takes part in the 

 * regeneration, 



(b) When only one new organ arises at the place of 

 injury. 



(o) When the appearanoe of "juvenile -forms", or primi- 

 tive developmental stages, do not exclude agreement 



Processes of restitution, "by which an organ is produced en- 

 tirely similar to the one lost, are rare in the plant kingdom. 

 Roots from which the extreme tips hr.ve been removed regenerate 

 the lost part^. According to Peters, the tip of the sprott of 

 Smal^f Helianthus plants is capable of regeneration , According 

 to Gobel^ the prothalllum of the Polypodiaceae, the pseudo-bulbs 

 of Drepanophyllum and Eriopus, if injured by grazing animals, 

 can likewise regenerate the lost part . The question, whether 

 mutilated leaves are also able to regenerate parts that have- been 

 lost, until most recently an open questipn, has just b#en affirm- 

 atively answered by the 'experiments of Gobel° on Poly podium Her - 

 aoleum and by Pisohinger's° on Streptocarpus and Monophyllaea, 

 If finally, we include the new structures on wounded unicellular' 

 organisms (Siphoneae), to which we shall return later, then all 

 known forms of true restitution in the plant world will have 

 been named, 



(10) Observations similar to these on the restoration of whole 

 organs and organisms may be made on the restitution of cells and 

 tissues. It will be necessary to make Investigations in order to 

 see whether the cells, injured by the mutilation of any portion 

 of the plant, are healed by the regeneration of their membrane, 

 their protoplast and so forth, thus regaining their original form 

 or composition:- entirely independent of the question, whether 

 the organism as a whole resumes at the same time its former size 

 §nd normal form. In the second place, the question must be dis- 

 cussed, whether, after injury, a tissue can be produced from the 

 parts there exposed, which agrees in all particulars with the 

 normal superficial tissues;- in other words, whether, at the 

 place of injury, a normal epidermis or a normal membrane of any 

 kind whatever can be formed, no matter if the reproduction of 

 such tissue is connected with a complete compensation for organs 

 possibly lost. 



^ Ciesielski, Untersuch. uber die Abwartskrummungen der 

 Wurzel. Cohn's Beijr. z. Biol. d. Pflanz., 1872, Bd. I, p, 21; 

 Prantl, Untersuch. ub. d. Regeneration d. Vegetationspunktes an 

 Angiospermenwurzein. Arb. d. Wurzburger Institutes, 1874, Bd.I, 

 p, 546. Roots cut in half longitudinally are also capable of re- 

 generation. Compare Lopriore, Ueb, d. Regeneration gespaltener 

 - Wurzeln. Hova j^cta Ac, Leop, CJarol., 1896, Bd^ LXVI, p. 233. 



2 Pdters, Beitr. z. Kenntnis d. Wundheilung bei Helianthus 

 annuus t. und Polygonum cuspidatum Sieb. u. Zucc. Diss. Gotting-- 

 en, 1897, p. 109. 



*? n 



Or ganogr aphis, Bd. I, p, 37; further, Uber Regeneration 



im Pflanzenreich, Biol, Centralbl, , 1902, Bi. XXIl, p, 385, 



4 If 



Uber Regeneration im Pflanzenreich, loc, cit. p» 508, 



Therein references to unsafe statements on leaf re-gene rat Ion. 



Correns, Untersuch. ub, d. Vet-mehrung d» iStibmcose, 1899, 

 p. 57, 58, 236, '. ' " . < 



J,, j^ !j' '! ■ _ -• . _ 

 ^ Ueb, Bau u. Regeneration 6.6ptA^n±milktibn8p^pv^f^tG& Vdn 

 Streptocarpus und }IIdnoph.yllaed>{ ffi^^ungsberV Akaft/ wlss< Vien, 

 Math. Haturw. Cl.» 'l5C2^ Bd/ <m, Abt/ 1/ p/' Z78i 



