REJUVENESCENCE IN NATURE. 101 



whereby space is gained for its new uprising in the fruit- 

 formation.* 



Let us now turn from the examination of the undulation 

 which the metamorphosis of the plant follows in its 

 greater soarings and subsidings, to the consideration of 

 the individual steps in which it completes its course, the 

 single leaves. The leaves present themselves to us as 

 the single waves in the great stream of vegetable develop- 

 ment, a stream flowing and ebbing with a periodicity 

 regulated by law. As we have regarded the sprout as 

 the first subordinate Rejuvenescence of the plant, as we 

 have further considered the regions and formations on the 

 sprout as circles of Rejuvenescence of the metamorphosis, 

 so have we now to examine the in dividual leaves (with the 

 internodes bearing them,) as links of Rejuvenescence 

 within these larger circles. In this sphere, the theory of 

 Rejuvenescence already presents itself to us in a declared 

 form and developed into a system in recent scientific 

 literature,! but truly, in spite of much that is to the point 



* At the same time, all diclinous flowers do not behave in the same way; 

 on the contrary, there exist great and essential differences in the structure 

 of flowers with separated sexes, which, however, are often difficult to make 

 out. While in the cases above considered the unisexual flower presents 

 itself merely as a one-sided development of an hermaphrodite flower, its 

 origin depends in other cases, like the sex in animals, on the different mode 

 of development of parts, which, according to their position in the flower, are 

 like, as is the case, for example, hi the Willows, in which the same leaves 

 appear in the male as stamens and in the female as carpels. The observa- 

 tions which I have made on the so-called hermaphrodite flowers of Carex, in 

 particular of Carex slricta, seem to testify the same for this genus. In 

 Hydrocharis we meet with a case which stands mid-way between the two 

 mentioned modes of origin of unisexual flowers, tn this plant the flower is 

 composed of six alternating trimerous whorls. The first and second (calyx 

 and corolla) behave alike in the male and female flowers. The third, fourth, 

 and fifth, appear as perfectly developed stamens in the male flower, while 

 the sixth consists of blunt processes which sometimes have been called stami- 

 nodia, sometimes abortive pistils. In the female flower, on the contrary, the 

 third and fourth whorls appear as blunt processes, (staminodia and nectaries 

 of authors) while the fifth and sixth become fully developed in the fonn of 

 carpels. 



f C. H. Schultz, 'Die Lehre von der Anaphytose oder Verjungnng der 

 Pflanzen, eiu Schiissel zur Erklarung des Wachseus, Bliihens und Fruch- 

 tragens der Pflanzen,' 1843 ; and ' Neues System der Morphologic der 

 Pflanzeu nach den Orgauischen Bildungsgesetzen,' 1847. 



