RUJUVENESCENCE IN NATURE. 83 



side of the first region,) as in Gentiana;* while, on the 

 other hand, the leaf-formation often sinks down before 

 the transition into flower, to complete disappearance of 

 the leaf, which as it were emerges anew in the 

 flower. Within the general lines of rise and fall, even, 

 occur other subordinate lines of undulation, correspond- 

 ing to the individual formations, which will be briefly 

 touched upon hereafter. Every plant has its proper vital 

 lines for these vibrations of the metamorphosis, the 

 constructive representation of which lines will make 

 clearly conceivable, characters which botanists have 

 hitherto only seized in the most fragmentary manner, or 

 have felt obscurely as something indescribable in the habit. 

 A particularly important phenomenon belonging to 

 this series is the occurrence, at determinate points of 

 transition of the metamorphosis, of the above-mentioned 

 disappearance or non-appearance of leaves which exist in 

 rudiment, but either do not come to full development, or 

 are suppressed in the earliest stages of formation.! This 

 dipping down of the leaf-formation, occurring so frequently, 

 and connected with determinate regions, J is the best evi- 

 dence of the undulating course of the metamorphosis, and 

 the best criterion for the separate sections. Disappearance 

 of this kind occurs at four different places in the process 

 of the metamorphosis, namely, first at the two points of 

 depression, already considered above, at the points of 

 transition of the three chief regions one into another, 

 from stock to flower and from flower to fruit ; and at two 



* See especially G. campestris, in which the first two sepals are com- 

 pletely foliaceous. 



f This phenomenon belongs to what botanists call abortus, against the 

 multifold groundless and superficial assumptions of which Schleiden very 

 justly inveighs repeatedly, (' Grundziige,' ii, 188.) The correct application 

 of the comparative method will guard us from such idle speculation, and 

 indicate to us with certainty suppression of leaf -formation, even in cases 

 where observation of the course of development is perhaps never capable 

 of affording a demonstration. 



% Another series of abortions, here left entirely out of view, is connected 

 with the zygomorphic and antagonistic structure of what are called irregular 

 flowers. 



