340 



ORGANOGRAPHY. 



The cotyledons are commonly sessile, . and their margins are 

 usually entire, but exceptions occur to both these characters ; 

 thus in Geranium molle [fig. 754), they are petiolate ; while in 

 the Lime {fig. 744), and Geranium {fig. 754), they are lobed. 



The cotyledons also vary in their relative positions to each 

 other. Generally they are placed parallel, or face to face, as 

 in the Almond {fig. 749), Pea {fig. 14), and Bean already 

 referred to ; but they frequently depart widely from such a re- 

 lation, and assume others, analogous to those already described 

 in speaking of the vernation of leaves and the sestivation of the 

 floral envelopes. Thus each of the cotyledons may be either 

 reclinate, conduplicctte, convolute, or circinate. These are the 

 commoner conditions, and in such instances both cotyledons are 

 either folded or rolled in the same direction, so that they 

 appear to form but one body ; or in rare cases the cotyledons are 

 folded in opposite directions, and become equitant or ohvolute ; 

 or other still more complicated arrangements sometimes occur. 



The position of the radicle in relation to the cotyledons is also 

 liable to much variation. Thus the radicle may follow the same 

 direction as the cotyledons, or a diiferent one. In the former 

 case, if the embryo be straight, the radicle will be more or less 



Fig. 755. Fig. 756 



Fig. 759. 



Fig. 755. Vertical section of the seed of the Pansy, h. Hilum. pi. Embryo 

 with its radicle, r, and cotyledons, co. ch. Chaliiza. al. Albumen, ra. 



Raphe. Fig. 756. Vertical section of the seed of the Poppy, with the 



embryo sliglitly curved in the axis of albumen. Fig. 757. Vertical 



section of the seed of Bimias, .showing its spiral embryo. Fig. 758. 



Embryo of the Woad (Inatis tinctoria). 1. Undivided. 2. Horizontal 

 section, c. Cotyledons, r. Radicle. Fig. 759. Embryo of the Wall- 

 flower. 1. Undivided. 2. Horizontal section, r. Radicle, c. Coty- 

 ledons. 



continuous in a straight line with the cotyledons, as in the 

 Pansy {fig. 755, r) ; if on the contrary the emliryo is curved, the 

 radicle will be curved also {fig. 756), and sometimes the curva- 

 ture is so great, that a spiral is formed, as in Bunias {fig. 757). 

 In the latter case, where the direction of the cotyledons and 



