THE COMMENCEMENT OF THE PHANEROGAMIC FRUIT. 75 



occupy positions within the cup those immediately at the apex being at the 

 centre whilst those near the base will be found on the edge of the cup. 



According as the leaves are inserted spirally or in whorls upon the receptacle, 

 whether they are present in single or double cycles, whether they are fused with 

 one another or with the receptacle all these offer almost infinite possibility of 

 variation in form, so manifold, indeed, that their complete description is quite 

 beyond the limits of the present work. Here the forms described must be 

 limited to a series of more or less typical cases; they are for the most part 

 selected from well-known and widely -distributed plants readily accessible to 

 any one. 



To avoid repetition the seventeen selected cases are arranged in two groups, of 

 which the first group includes forms with a conical receptacle, the second such as 

 have a disc-like or excavated receptacle. Each of these groups is further sub- 

 divided, according as the carpels are all of one sort or of two sorts. 



OVAEIES ON A CONICAL RECEPTACLE. 



Carpels all of One Sort. 



(1) The carpels are inserted spirally on the receptacle. Each carpel contains 

 one or several ovules. The receptacle is either much elongated, as in the Mousetail 

 (Myosurus, figs. 207 8 and 207 9 ), or conical, as in the Tulip-tree (Liriodendrori), or 

 button-like, as in the Crowfoot (Ranunculus). 



(2) The carpels are inserted in whorls upon the receptacle, their margins are 

 infolded and fused with the prolonged apex of the receptacle. Since they are also 

 fused with one another below, they collectively form a multilocular ovary. Each 

 carpel bears ovules over its inner surface. As examples may be quoted the Yellow 

 Water-Lily (Nuphar), and the Flowering Rush (Butomus, figs. 210 7 and 210 8 ). 



(3) The carpels are inserted in a whorl at the summit of the receptacle and are 

 fused with one another. The receptacle does not project into the ovarian cavity. 

 Each carpel bears ovules either along its margins, as in Mignonette (Reseda, 

 figs. 207 3 and 207 4 ), or on its internal surface, as in the Sundew (Drosera), or 

 basally, as in Dioncea, Drosophyllum, and in Caylusea (Resedacese). In Reseda the 



ovary is open above. 



Carpels of Two Kinds. 



(4) The carpels arise at the tip of the receptacle in two alternating whorls of two 

 each. The two upper carpels are reduced to midribs on which the ovules are borne 

 in two rows. A delicate membrane is stretched like a tympanum between these two 

 midribs which form the frame. The two lower carpels are destitute of ovules and 

 are fixed like valves to the upper pair. This form is met with in numerous modifi- 

 cations in the Cruciferse. 



(5) The carpels arise in two whorls at the tip of the receptacle. Those of the 

 lower whorl are destitute of ovules and form the ovary, those of the upper whorl 

 are modified into strings or cushions, and are fused with the inner surface of the 



