98 The Waterlilies. 



arise on the sides, and later the posterior sepal. Hence comes their 

 peculiar aestivation. Four papillae next appear alternate with the sepals. 

 They arise simultaneously, grow rapidly, and are always larger than the 

 inner floral organs, which originate later. They are at the base of a hemi- 

 spherical receptacle whose surface, naked hitherto, becomes covered little 

 by little from base to summit with a number of new papillae. These are 

 arranged in ten vertical rows, one abutting on each petal, one on each 

 lateral sepal, and two on the posterior and anterior sepals. The lowest 

 ones soon flatten out and become petals ; the uppermost become typical 

 stamens ; between these two sets one finds all gradations from stamen to 

 petal. The stamen rudiments, however, do not cover the whole recep- 

 tacle. A bare space remains at the summit, around the edges of which a 

 row of papillae appears. These (the carpels) become horse-shoe shaped, 

 and their inner edges join, making a sinuous line. The sinuosities extend 

 somewhat toward the center, and a thick process of the receptacle grows 

 up to fill the central space, closing the ovary-cells. Now the sepals and 

 the four outer petals remain stationary, as it were, while the rest of the 

 receptacle elongates, carrying with it the carpels, stamens, and inner 

 petals. Thus the ovary comes to be inferior with regard to the stamens 

 and inner petals while the outer petals and the sepals have an inferior 

 insertion. There is no fusion of the floral leaves outside the carpels with 

 the ovary or receptacle, as Koehne {fide Goebel) believed. 



According to this account from Payer, the ovary would bear the 

 carpels at its summit, and its lower parts would be of axial origin. Goebel 

 (1. c.) noted this difficulty and showed that before the carpels are mapped 

 out there is a hollowing of the receptacle as is common in inferior ovaries. 

 From the edge of the axial excavation, but reaching to the bottom of it, 

 arise the carpel-rudiments. They are never free from the receptacle on 

 the outer side. The whole wall of the ovary-cells, however, is of carpellary 

 origin, and no part is formed from the vegetative apex of the flower stalk. 

 Our own observations on N. caerulea and lotus support Goebel's view. 



In N. lotus the time relations of the origin of the outer floral organs 

 differ slightly from that given by Payer. In the apex of a large flowering 

 plant we found three rudimentary flowers of successive ages and sizes, in 

 all of which only the anterior and lateral sepal-rudiments were present 

 (Fig. 45, a, b). This shows that these organs originate much earlier than 

 those farther in. The anterior sepal was much larger than the others, and 

 was inserted considerably farther down. In such a rudiment one could 

 hardly speak of a peduncle, for this sepal seemed almost sessile on the 



