REJUVENESCENCE IN NATURE. 81 



nected therewith. In the first region, indeed, the 

 euphyllary formation exhibits the maximum in this 

 respect also ; in the flower, on the contrary, it is not the 

 corolline but the staminal formation which represents the 

 maximum in relation to internal subdivision, since we 

 detect in the latter the most distinct separation of 

 petiolar and laminar formations. Even vaginal and 

 stipuloid expansions and appendages now and then occur 

 at the base of the stamens, still further confirming the 

 analogy with the euphyllary formation. The same 

 position also denotes the physiological importance of 

 the staminal leaves; for euphyllary leaves, staminal 

 leaves, and carpellary leaves, are evidently the three most 

 essential leaf-formations, to which the most important 

 physiological functions are distributed, and without which 

 a perfect and complete plant is inconceivable,* while 

 there is a possibility of all the rest being omitted. At 

 the same time I have hitherto searched in vain through 

 the Vegetable kingdom for a plant devoid of all the 

 inessential formations at once, possessing, that is, really 

 only leaf, stamen, and fructification. 



The maxima of the leaf- formation are again differently 

 distributed when we take the consistence and persistence 

 of the leaves for a standard. In the first region the 

 euphyllary leaves claim the highest place in this respect 

 also, for although succulent and fleshy cataphyllary leaves 

 are not rare, the majority of them are soon killed by the 

 growing warmth of spring, while the euphyllary leaves of 

 very many plants, fleshily succulent as well as leathery, 

 are of several years' duration.! In the flower, the 

 calyx has the greatest durability, thereby showing a 

 relation on the one hand to the euphyllary formation, 



* Only such plants as do not elaborate their own nutriment, parasites on 

 living plants and parasite-like vegetables which are nourished like Fungi on 

 decaying remains, can dispense with the leaf-formation. 



f Ex. gr. in the Cycadea?, Conifers, Palma3, Aloe, and Agace, Crassu- 

 Iacea3, Aizoidea, Buxus, Ilex, Citrus, Laurus, and the endless host of ever- 

 green trees of the tropical zones. In the silver fir the duration of the 

 acicular leaves extends to seven or eight years. 



6 



