238 ON THE SEED. 



The pedicel conveys nourishment to the embryo plant. 

 When the seed is ripe, this communication ceases, the 

 pedicel withers and dries, and the seed detaches itself. 

 This scar which you see on the testa, and which inter- 

 rupts its uniform smoothness, is made by the rupture of 

 the pedicel, and is always considered as the base of the 

 seed ; and you may still perceive the small aperture 

 through which the nutritive juices passed into the seed. 



Emily. But is not the embryo plant nourished by ab- 

 sorbing the amnios ? 



Mrs. B. Not wholly ; for you must consider that it 

 not only requires food for its immediate sustenance, but 

 lays up a store of provision in its cotyledons, which is re- 

 served for its future growth at the period of germination. 

 Caroline. I always thought that those little threads 

 which fastened peas and beans to the pods were merely 

 to prevent their rolling about in the shell ; but now I see 

 that it is necessary they should have a communication 

 with the pod, for the conveyance of nourishment. 



Emily. What vessels in miniature these must be ! I 

 know nothing more curious than the extreme, I may al- 

 most say the invisible, minuteness of some of the organs 

 of plants. 



Mrs. B. In some seeds, the whole of the amnios is 

 consumed by the embryo plant ; in others, the absorption 

 of this liquid is only partial : the most fluid parts pass in- 

 to the embryo, while the more solid particles, being prob- 

 ably too bulky to traverse such minute vessels, are depos- 

 ited in the interior of the seed. This substance is, at 

 first, of the color and consistence of the white of egg, and 

 has thence acquired the name of albumen ; but, as the 

 seed approaches maturity, it coagulates, and adheres to 

 the endopleur, lining it throughout with a white concrete 

 substance, and, indeed, filling the whole of the space 

 which is not occupied by the embryo plant. This is a 

 resource afforded by Nature for the germination of seeds 

 which have not a sufficient store of food in their fleshy 

 cotyledons. 



Caroline. But peas and beans are so well supplied by 

 these cotyledons, that they are in no want of such resource. 



1300. What is said of the scar on the testa! 1301. Emily asks, 

 if the embryo plant is not nourished by absorbing the amnios what is 

 the answer! 1302. How is the conversion of the amnios into the em- 

 bryo, in different seeds described! 1303. What is albumen, from what 

 dues it derive its names, and what agency does it have in the formation 

 of the plant. 



