PHANEROGAMIA: FLOWERS. 

 897 



395 



236 



238 



In the formation of the integuments, the conditions and relations of 

 the individual parts particularly deserve a closer investigation. 



In the first place, I must remark that the term nucleus, as used in con- 

 tradistinction to the integuments, designates only that portion of the ori- 

 ginal little conical body, which, in the beginning above the integuments, 

 becomes covered up by these, and to which the micropyle canal leads. The 

 relative size and the form of this nucleus are very various ; it usually 

 forms a small ovate body, being thicker above the base, and then gra- 

 dually narrowed towards its summit (fig. 239.) ; but it is also frequently 

 a long cylinder (in many Scrophulariacce, as, for example, Pedicularis 

 (fig. 240.) ; frequently, it is a mere blunt cone (as, in Podostemon\ or a 

 hemisphere (as in Convolvulus, fig. 241.), or even little more than a mere 

 point to which the micropyle canal leads, whereby alone such a seed-bud 

 is distinguished from a naked nucleus (for example, in Scabiosa, fig. 242.). 



239 



240 



241 



242 



J 



836 Hellenia carulea. A, Seed-bud before impregnation : x, thickened border of the 

 exostome. #, The same in longitudinal section : a, funiculus and hilum ; b, nucleus ; 

 c, embryo-sac ; d, inner, and /, outer integument ; g, micropyle ; h, chalaza ; r, raphe ; 

 k, arillus. 



837 Scleranthus perennis. Seed-bud in longitudinal section, a, Funiculus and hilum ; 

 6, nucleus; c, embryo-sac; d, inner, and/, outer integument; g, micropyle; h, chalaza. 



838 Lathraa sqnainaria. Seed-bud in longitudinal section, a, Hilum ; b, nucleus 

 (as a nuclear membrane) ; c, embryo-sac, with its appendices; d, simple integument; 

 g, micropyle ; h, chalaza. 



239 Lilium spec. Seed. bud in longitudinal section, c, Nucleus ; m, nuclear papilla; 

 g, micropyle. 



840 Pedicularis palustris. Seed-bud in longitudinal section, c, Nucleus ; m, nuclear 

 papilla ; g, micropyle. 



811 Calystegia septum. Seed-bud in longitudinal section, c, m, Nucleus and nuclear 

 papilla ; g, micropyle. 



848 Scabiosa atropurpurea. Seed-bud in longitudinal section, c, m, .Nucleus and 

 nuclear papilla ; g, micropyle. 



