UEJXJVENESCENCE IN NATURE. 9 



The Vegetable kingdom of the ancient world likewise 

 exhibits a periodical progress corresponding to a gradation 

 of structure still existing, since the oldest periods have 

 exhibited scarcely anything but Flowerless plants (Crypto- 

 gamia), which are soon followed by the Gymnosperms 

 (Cycadacese and Coniferse), and in some degree by still 

 doubtful Monocotyledons, while the Dicotyledonous plants 

 appear distinctly latest. The results of geological re- 

 search appear to confirm, more and more, that all this 

 progress of organic nature, from the first onset to our 

 own time, has an essential connexion, and, although dis- 

 turbed in many ways by the catastrophes which the 

 earth has suffered, has never been altogether interrupted ; 

 in a word, that it represents a single history of develop- 

 ment, and not a series of separate and independent 

 creations. 



The ancient changes in the living garment of the earth, 

 appear then as Rejuvenescences of organic nature in mass, 

 and the individual genera and species of the organic 

 kingdoms as subordinate links in its great chain of 

 development. The fact that nature halted at determinate 

 points, in the calm intervals, and during the epochs pro- 

 duced, essentially at least, only the like, does not remove 

 the relation to the totality of the development. This is 

 the same phenomenon, on a grand scale, as when we see 

 the plant repeat itself in the same form, often hundreds 

 of times, at particular stages of its growth, before the 

 metamorphosis advances to a new stage, as for example, 

 often hundreds, or even thousands, of the ordinary 

 (euphyllary) leaves [Erica, Calluna, Tamarix Abies), bracts 

 (hypsophyllary leaves) (Bipsacus, Cnicus, Celosia), petals 

 {NymphcBa, Mesembryanthemum, Illicium), stamens [Pa- 

 paver, Billenia, Helleborus), or carpels {Myosurus, 

 Anemone, Anond), are formed in unbroken succession on 

 one and the same axis. But even in these times of 

 halting, by no means the absolutely like is formed. No 

 leaf, even when belonging to the same formation, exactly 

 resembles another ; and with every successive leaf, if the 



