SEED OR MATURE OVULE. 



277 



582. On the testa, at various points, there are produced at times 

 cellular bodies, which are not dependent on fertilization, to which the 



name of strophioles (strophiolum, a little garland), or caruncuks (carun- 

 cula, a little piece of flesh), has been given, the seeds being strophio- 

 late or carunculate. These tumours may occur 

 near the base or apex of the seed, they may be 

 swellings of the exostome, as in Eicinus (fig. 483 c), 

 or they may occur in the course of the raphe. 



583. Seeds are attached to the placenta by 

 means of a funiculus or umbilical cord, which 

 varies much in length. In Magnolias it attains a 

 great length, and when the seed is ripe it appears 

 like a cord suspending it from the follicle. The 

 point of the seed by which it is united to the cord 

 or the scar left on its separation, is called the hilum or umbilicus, and 

 represents its base. It frequently exhibits marked colours, being 

 black in the Bean, white in many species of Phaseolus, &c. It may 

 occupy a small or large surface, according to the nature of the attach- 

 ment. What constitutes the foramen of the ovule, becomes the 

 micropyle (fiixgo;, small, and Z-J/AH, gate) of the seed, with its exostome 

 and endostome. This may be recognizable by the naked eye, as in 

 the Pea and Bean tribe, Iris, &c , or it may be very minute and 

 microscopic. It indicates the true apex of the seed, and is important 

 as marking the part to which the root of the embryo is directed. At 

 the micropyle in the Bean, is observed a small process of integument, 

 which, when the young plant sprouts, is pushed up like a lid, and is 



Fi^. 482. Development of the same arillus, or, around the ovule, o, exhibited in a different 

 position. 1, 2, 3, 4, are four succesive stages of development. In fig. 4, the arillus has been cut 

 vertically, to show its relation to the ovule, which it surrounds completely. 



Fig. 483. Vertical section of a carpel of Ricinus communis, and of the seed which it contains, 

 n, Pericarp. Z, Loculament /, Funiculus or umbilical cord, t, Integuments of the seed, having 

 at their apex a caruncula, c, which is traversed by the small canal of the exostome. The exos- 

 tome does not correspond exactly with the endostome, which is immediately above the radicle. 

 r, Raphe. c h, Chalaza. ft Perisperm or albumen, the upper portion of which only is seen 

 e, Embryo, with its radicle, e r, and its cotyledons, c. 



