REJUVENESCENCE IN NATURE. 95 



accurately make out the conditions of relationship. Thus, 

 for example, the genus Glauoa agrees so closely with the 

 type of the very sharply-defined Primulaceae, that we 

 have no hesitation in ascribing the apetalous condition of 

 this genus to the suppression of two circles of petals. 

 The Chenopodiaceae, Amarantaceae, and Sclerantheae, are 

 connected so unmistakeably with the petaliferous families 

 of the order of the Caryophyllaceae, particularly with the 

 Alsinete, that we at once regard them as Apetalae pro- 

 duced by the suppression of the corolla, especially when 

 we take into consideration how such a suppression occurs 

 in particular cases among the Silenea and Alsinece, and 

 may even be demonstrated in one and the same species, 

 sometimes in all gradations, as for instance, in Stettaria 

 media, which is found with very different sizes of the 

 petals down to complete abortion of them (var. apetala). 

 The conditions are similar in the apetalous state of 

 Peplis among the Lythrarieae, Isnardia among the 

 Onagreae, Chrysosplenium among the Saxifrageae, Sterculia 

 among the Tiliaceae, and Pistacia among the Terebin- 

 thaceae. In Pliytolacca decandra, the quinate corolla 

 vanishes together with a ten-membered outer circle of 

 stamens, which latter exists perfectly developed in Ph. 

 icosandra. 



I will only add, to these already too widely extended 

 remarks on the subordinate retrogression of the leaf- 

 formation which is frequently interposed at the tran- 

 sition to the stamen-formation, and which causes an 

 independent separation and uplifting of this most im- 

 portant section of the flower, that the ascending condition 

 in the succession of stamens or of circles of stamens, 

 mentioned above as an apparent exception,* is explained 

 by this, corresponding exactly to the rise in the magni- 

 tude of the hypsophyllary leaves, which we have already 

 examined.! This phenomenon is met with, for example, 

 in Aloe, Anthericum, Ornithogalum, in which the three 



* See page 80. t See page 85. 



