SECT. I. ORGANOGRAPHV AND GLOSSOLOGY. 



Ill 



123 



nected with the physiology of our subject, we shall for 

 the present confine ourselves to a few 

 general observations .on the ripe seed. 

 Every seed is attached to the placenta, 

 by what is termed a " funicular, or um- 

 bilical cord;" and when the seed has 

 fallen from the pericarp, it is marked by 

 a scar or " hilum," at the place where 

 this cord was attached to it. In very 

 many cases, this cord is small, and 

 scarcely distinguishable, but in some it 

 is well marked ; and in the genus Mag- 

 nolia, when the pericarp bursts, the seeds 

 hang out for some time, and to a con- 

 siderable distance, by means of their 

 umbilical cords, before they become de- 

 tached and fall to the ground (^z#. 124.). 

 In a few plants, the funicular cord is 

 unusually developed ; and, rising round 

 the seed, forms a distinct skin or covering 

 termed an " arillus." The 

 nutmeg (fig. 125.) is thus 

 enveloped by an arillus, 

 which is the cc mace" of com- 

 merce. In the spindle-tree 

 (Euonymus europceus), the 

 seeds are invested by an arillus, 

 of a fleshy consistency and 

 bright scarlet colour. 



In its ripe state every seed 

 is essentially composed of an 

 outer skin, or " spermoderm," 

 and a " kernel" within it. The 

 spermoderm, however, is not 

 a distinct organ, but is rather 

 the dry and exhausted remains of two or more coats, 

 with which the embryo was invested in its earliest 

 state, but which have ultimately united, and form 

 a single skin on the ripe seed. The kernel consists 



