REJUVENESCENCE IN NATURE. 71 



to the conditions of breadth, for the cotyledons of many 

 plants are longer and larger than the succeeding leaves 

 of the principal sprout, as, for example, in Quercus, 

 Vicia, Casuarina, Opuntia, &c. The increasing length 

 in the succession of cataphyllary-leaves, may be seen in 

 beautiful gradation almost everywhere on the subter- 

 raneous buds of perennial herbs, and on the buds of 

 trees ; see, for instance, Paonia, where the 6 7 lower 

 leaves show graduated increase from 3 lines to 14 inch,* 

 Mahonia Aquifolium, where they increase from 1 to 6 

 lines, ^Esculus,\ Rosa,\ Rhododendron,*} &c. The 

 increasing length and magnitude of stem -leaves in 

 germinating plants is especially well seen in Acer, 

 Corylus, Vitis, Phaseolus, &c. The increasing length of 

 the leaves is mostly continued, more distinctly in the 

 euphyllary than in the cataphyllary formation, till it 

 reaches its maximum in a determinate median region, 

 from which an equally graduated decrease commences, 

 mostly prolonged even into the hypsophyllary region. 

 It depends on the conditions of extension of the stem 

 whether the maximum of the longitudinal development of 

 the euphyllary leaves lies in the lower abbreviated part 

 of the stem, so that all the euphyllary leaves situated on 

 the developed internodes belong to the decreasing series ; 

 or, when no such rosette-like crowding of the lower 

 euphyllary leaves exists, at a determinate height on the 

 shoot itself. || Examples of the first kind are seen in 

 Nigritella angustifolia^ Chrysanthemum Leucanthemum, 



* Decandolle, ' Organographie,' t. xxi, figs. 1, 3. 



t Ibid., t. 20. 



% Malpighi, 'Anat. Plant,, t. xii, fig. 59. 



Henry, ' Knospenbilder,' Nova. Acta. Nat. Cur., xxii, 1, t. xxii. 



|| Both conditions are found combined, consequently a double maximum 

 in the euphyllary formation, a lower in the abbreviated part of the stem (in a 

 rosette of what are termed radical leaves), and an upper, on the shoot, 

 mostly, it is true, distributed through two seasons, in many biennial plants, 

 e. ff., Pedicularis palustris, Anarrhinum bellidi folium, (Enothera muricata, as 

 also in perennials with biennial sprouts, e.g., Jasione perennis and Pulmonaria 

 officinulis. This phenomenon, however, does not properly belong here, but 

 to the case mentioned above at page 59 of retrogressive metamorphosis 

 within the euphyllary formation. 



