FOUNDATIONS OF BOTANY 



--cot. 



Observe particularly how the sand is pushed aside by the rise of 

 the young seedlings. Suggest some reason for the manner in which 

 the sand is penetrated by the rising stem. 



2. Examination of the Squash Seed. — 

 Make a sketch of the dry seed, natural size. 

 Note the little scar at the pointed end of the 

 seed where the latter was attached to its 

 place of growth in the squash. Label this 

 hilum. 



Note the little hole in the hilum ; it is 

 the micropyle, seen most plainly in a soaked 

 seed. (If there are two depressions on the 

 hilum the deeper one is the micropyle.) 



Describe the color and texture' of the outer 

 coating of the seed. With a scalpel or a very 

 sharp knife cut across near the middle a seed 

 that has been soaked in water for twenty- 

 four hours. Squeeze one of the portions, 

 held edgewise between the thumb and finger, 

 in such a way as to separate slightly the 

 halves into which the contents of the seed is 

 naturally divided. Examine with the mag- 

 nifying glass the section thus treated, 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 (Fig. 

 1, e), with which the kernel of the seed is 

 closely covered.! 



Strip this off and sketch the uncovered ker- 

 nel or embryo. Note that at one end it tapers 

 to a point. This pointed portion, known 

 as the hypocotyl, will develop after the seed 

 sprouts into the stem of the plantlet, like that shown at c in Fig. 2. 

 Split the halves of the kernel entirely apart from each other, 

 1 See footnote 2 to Sect 18. 



--C 



h 



Fig. 1. — Lengthwise Section 

 of a Squaah Seed. (Magni- 

 fied about tire times.) 



