REJUVENESCENCE IN NATURE. 53 



they are sent out either dies {Solanum tuberosum, Sasei- 

 fraga granulatd), or becomes a mere supporting and 

 subservient scaffold, to a certain extent a soil for the new 

 generation, so in the Rejuvenescence in the sprout itself, 

 we again find these two cases, since the fore-rmining 

 part of the sprout sometimes dies away, sometimes be- 

 comes the support of the i-ejuvenised continuation. The 

 first case is seen in all root-stocks dying away at the 

 posterior end,* as also in bulbsf dying away externally 

 and becoming rejuvenised in the centre ; the latter we 

 find especially in woody plants which possess terminal 

 buds. On the other hand, there is the essential dis- 

 tinction, in morphological respects, between the two 

 cases here compared, that in the one case the renovated 

 vital movement is undertaken by really new individuals 

 (lateral sprouts), while in the other cases the same indi- 

 viduals (the old sprouts), rise up to new vital activity, 

 which distinction has already been remarked upon above, 

 in the introductory consideration of the buds.| Moreover 

 those sprouts which are incapable of advancing to the 

 uppermost stage, do not in all plants possess the power 

 of Rejuvenescence through retrogression to a lower stage 

 of formation, i. e. the power of forming terminal buds 

 destined for the succeeding period of vegetation ; this is 

 rather, indeed, a privilege of but a few perennial herbs 

 with subterraneous perennial stocks, and of a portion of 

 the woody plants. § Among those which possess this 

 power, again, two cases have to be distinguished : either 



* Anemone nemorosa, Epimedium alpimim. 



f Narcissus, for example. The terrestrial species of Isoeies, particularly 

 /. hystrix and /. Duriaei, afford an especially fine instance of this kind. See 

 my description of them in the ' Exploration Scientifique d'Algerie.' 



± Distinction of lateral and terminal buds, pp. 18-20. 



I formation of terminal buds does not occur, for instance, on the middle 

 leaf-bearing chief sprout of TJrtica nrens and Mercurialis annua ; since these 

 plants are also devoid of lateral buds, they die away altogether after the 

 fruit is quite matured. Urtica dioica, and Mercurialis perennis die down 

 only to the cataphyllary region, from which arise the cataphyllary sprouts 

 lasting over the winter. Carpinus, Salix, JJlmus, Morns, Madura, Tilia, 

 Biospyrus, and Galycanihus, are examples of woody plants without terminal 

 buds. 



