THE LIFE AND GROWTH OF SEEDLINGS 5 



be seen oozing out through a little hole, situated between the 

 apex of the radicle and the black scar. It is through this hole 

 that the root pushes its way. On removing the seed-coat the 

 greater part of the seed is found to be occupied by two thick, 

 fleshy lobes ; these are the cotyledons, or first leaves, of the 

 young plant. It is these that contain the food for the seedling. 

 Between the cotyledons a structure continuous with the radicle 

 is seen, namely, the plumule ; this gives rise to the young shoot. 

 In the case of the bean, then, the seed consists of 



1. The seed-coat. 



2. The embryo or young plant, the parts of the embryo being 

 the two cotyledons, the radicle and the plumule. Note that the 

 embryo fills the seed, and that the food for the young plant is 

 contained in it. 



With the bean may be compared the buckwheat. The 

 seed sold by the seedsman is a fruit, for the outer brown coat 

 is the wall of the ovary. It is a three-sided nut. On soaking 

 these nuts for twenty-four hours, they swell owing to the absorp- 

 tion of water. The outer coat is then softer and can easily be 

 peeled off, exposing the thin seed-coat, or testa, immediately 

 underneath it. The whole seed then appears to be filled with a 

 mealy substance. This is the food-material, called endosperm, or 

 albumen ; the food is outside the embryo, not contained in it, as in 

 the bean. On gently scraping away the endosperm, the embryo 

 is visible. The cotyledons are thin leaves folded in the endo- 

 sperm, the radicle lies at the apex of the seed and the plumule 

 lies towards the opposite end. This seed then resembles that 

 of the bean in having two cotyledons, a radicle and a plumule ; 

 that is to say the embryos are alike in the two cases. It differs 

 from the bean in having the food-material outside the embryo. 

 It is an albuminous seed, whilst the bean is exalbuminous. 



GERMINATION OF BUCKWHEAT. The Buckwheat germinates 

 quickly in a moist, warm atmosphere. If several nuts are sown 

 in boxes of soil, one seedling can be taken up every day, in order 

 to see the stages of development. 



i. The nut swells, and the radicle, making its way through 

 the thin testa, bursts the outer coat of the nut at the apex by 



