THE SEED AND ITS GEKMINATION. 



make a sketch of it and label the shell or covering of the seed and the 

 kernel within this. 



Taking another soaked seed, chip away the white outer shell, called 

 the testa, and observe the thin, greenish inner skin, the tegmen, with 

 which the kernel of the seed 

 is closely covered. 



Strip this off and sketch the 

 uncovered kernel. Note that 

 at one end it tapers to a point. 

 This pointed portion, known 

 as the caulicle, will develop 

 after the seed sprouts into the 

 stem of the plantlet, like that 

 shown at he in Fig. 1. 



Split the halves of the kernel 

 entirely apart from each other, 

 noticing that they are only 

 attached for a very little way 

 next to the caulicle, and ob- 

 serve the thickness of the 

 halves and the slight uneven- 

 ness of the inner surfaces. 

 These halves are called seed- 

 leaves or cotyledons. 



Have ready some seeds 

 which have been soaked for 

 24 hours and then left in a 

 loosely covered jar on damp 

 blotting-paper at a tempera- 

 ture of 70° or over until they 

 have begun to sprout. 



Split one of these seeds 

 apart, separating the cotyle- 

 dons, and observe, at the junction of these, two very slender pointed 

 objects, the rudimentary leaves of tihe plumule or first bud. 



3. Examination of the Bean. — Study the seed, both dry and after 

 12 hours' soaking, in the same general way in which the squash-seed 

 has just been examined. i 



1 The larger the variety of bean chosen, the easier it will be to see and sketch the 

 several parts. The large red kidney bean or the horticultural bean will do well for 

 this examination. 



Fig. 1. — The Castor Bean and its Germination. 



I, longitudinal section of the ripe seed ; n, ger- 

 minating seed ; Ac, caulicle ; c, cotyledon ; 

 e, nourishment stored around the cotyledons ; 

 s, testa ; x, thickened knot at end of seed ; 

 w, primary root ; w', secondary roots. 



