SUPPLEMENT 99 



turbances in nutrition, or in the supply of water. The buds in the axils of the 

 cotyledon of Phaseolus, for instance, always shoot out if the growth in the 

 epicotyl is inhibited ; one cannot, however, ascribe this effect of the apical 

 region to the withdrawal of water or nutriment. The formation of roots always 

 takes place in shoots of Phaseolus above any transverse incision, but this is 

 not because the cells concerned contain more water than before, for the same 

 result takes place if the shoot be wilted, and it cannot be induced by longitu- 

 dinal incisions, even if these be immersed in water. KLEBS (1903) believed 

 that the root formation was due to water being supplied to the parts concerned, 

 but MACCALLUM and VOCHTING have shown that his view cannot be main- 

 tained. Hence there must exist varying relations of unknown nature between 

 the different parts of the plant, the suspension of which induces regeneration. 

 Relations of this kind are spoken of as correlations. 



11. Cf-i6,for which express . . . multiflorus. read since these parts have no 

 longer any functions to perform. In fact, the usual result is the casting off of 

 the leaf-stalk or the leafless stem, since regeneration cannot appear rapidly. 

 The plant rids itself of useless organs. It is quite enough, under certain con- 

 ditions, as WINKLER (1905) has found, to restore one of the functions of the 

 leaf, transpiration, by placing a small block of plaster of Paris at the end of the 

 petiole, to keep it alive for weeks, when under ordinary circumstances it would 

 quickly drop off. 



If the leaves be removed as fast as they unfold from the terminal bud, 

 anatomical changes take place in the stem adapting it to carry out assimilation 

 previously undertaken by the leaf. The stem develops more chlorophyll and 

 stomata, and its cortical cells elongate like palisade cells (BoiRiVANT, 1897 ; 

 BRAUN, 1899). The same sort of structure, only more pronounced, is per- 

 manently found in plants with small or evanescent leaves, e. g. Genista, Saro- 

 thamnus. Further, the vascular bundles in plants whose leaves have been 

 removed become reduced and do not increase in thickness. Thus there is a 

 relation between the leaf and the leaf-trace in the stem, a relation which may 

 be studied very effectively in the epicotyl of Phaseolus multiflorus. 



I. 22, after 1891 read , 1893 



II. 27-52, for In other cases . . . new functions, read Certain phenomena 

 observed by the author in the years 1891-1893 are, doubtless, as MONTEMARTINI 

 (1904) points out, results of wounding, which progress further towards the base 

 than the apex. The reason for this is especially the feeble differentiation of 

 the primary elements already laid down, while the inhibition of secondary 

 growth may also be explained by the enclosure of the leaf in plaster of Paris. 

 The author has no doubt that the differentiation of the leaf-traces might also 

 be prevented by inhibiting the development of the leaf sufficiently early. 



As in the cases mentioned the removal of an organ inhibited its function 

 and at the same time caused another organ to develop feebly or to die off, so, 

 conversely, an organ may be stimulated to new activities when some other 

 function is transferred to it. 



332, 11. 11-14, f or The need for ... demand, read Just as in the case of the 

 potato tubers, one can make a petiole take its place in the general system of 

 the plant, as, e. g., when Begonia leaves are planted with the bases of their 

 petioles in wet sand. The petiole remains alive for a long time, and some of 

 its vascular bundles exhibit conspicuous secondary growth (KNY, 1904). 

 DE VRIES (1891) had previously observed the same phenomenon in the petiole 

 of Pelargonium, which was stimulated to continued secondary growth by an 

 anomalous leaf-bud on it. 



11. 26-33, /or I* 1 this case . . . form them, read Neither structure is, how- 

 ever, of any use, for the plant has now no buds, and cannot produce any. 



G 2 



