STRUCTURE. 79 



and arranged symmetrically about the centre of the peduncle (Fig. 26). 

 Outside of each of these are two rather prominent but much smaller 

 canals, and in N. zanzibariensis each of these is followed by two more 

 quite evident canals. Many smaller scattered ones are always present. 

 Idioblasts are extremely scarce in the Lotos group, frequent in Apo- 

 carpiae, plentiful in Castalia ; fibrous (bipolar) idioblasts occur throughout 

 the peduncle in Eu-castalia and around the periphery of the upper part in 

 Brachyceras. Thyll-like masses of soft cells are frequent on the sides of 

 the larger air-canals in Apocarpiae, occasional in Lotos, and not found in 

 Castalia. 



Vascular bundles are distributed on the same principle as in the 

 petiole (Fig. 26). In the centre is a large double or triple bundle. Oppo- 

 site each of the 4 or 6 main partitions there is a large double bundle, often 

 with two well-formed air-canals in Apocarpiae and Castalia, but with the 

 second canal a mere fissure without definite wall in Lotos. Midway 

 between these bundles are smaller ones, and so on in several series, 

 according to the size of the peduncle. Examples are shown in detail in 

 the diagrams. The constituents of the bundles are exactly as described 

 for petioles. 



Just beneath the flower the peduncle widens out to form a receptacle 

 for the insertion of the floral organs. This widening extends over about 

 1.3 cm. in Lotos, making an inverted frustum of a cone with a slope of 

 about 45. In Apocarpiae, Hydrocallis, and Eu-castalia the transition is 

 more sudden, almost like the limb of a salver-form corolla. The resulting 

 receptacle is usually round, but in Chamaenymphaea its upper margin is 

 square, with distinct and prominent angles. In Xanthantha there are four 

 rounded prominences on the sides of the receptacle, with distinct grooves 

 between ; the grooves are continued down a short distance on the petiole, 

 but they swell again quickly above, so that the receptacle is nearly round 

 at the line of insertion of the sepals. The color of the receptacle is usu- 

 ally like the peduncle, but paler. Within the upper part of this region 

 the vascular bundles of the peduncle unite into an extremely complex 

 horizontal network, from which bundles are separated out for the floral 

 organs. The complexity of this anastomosis is too great to admit of any 

 definition or unraveling as yet. 



The flower proper has four sepals, of which one is anterior and outer. 

 The two lateral sepals are covered on one edge by the anterior one, and 

 on their posterior sides they overlap the posterior sepal. At times three 

 or five sepals may occur. I have seen the smaller number in N. rubra 



