THE SEED 



17 



blue or a brown reaction ? Crush another bit of it on a piece 

 of white paper and see if it leaves a grease spot. What does 

 this show that it contains ? Test the embryo in the same way, 

 and see whether it contains any oil. 



NOTE. It should be borne in mind that the castor bean bears no rela- 

 tion whatever to the true beans. It belongs to the spurge family, which 

 is botanically very remote from that of the peas and beans. 



C 



h. - 



-p 



23 24 25 



FIGS. 23-25. Seed of a squash ; 23, seed from the outside ; 24, vertical section 

 perpendicular to the broad side ; 25, section parallel to the broad side, showing inner 

 side of a cotyledon ; a, seed coat ; c, cotyledons ; h, hypocotyl ; p, plumule. 



14. Study of a squash or gourd seed. How does the coat 

 of a squash seed differ from that of the bean ? At the small 

 end, look for two dots, or pinholes, close 

 together. Refer to your drawing of the 

 bean and see if you can make out, with 

 the help of a lens, what they are. The 

 bean is a curved seed, which is bent so as 

 to bring the hilum close to the micropyle 

 on one side. But by far the greater 

 number of seeds are inverted, or turned 

 over on their stalks, as you sometimes 

 see huckleberry blossoms and bell flowers 

 on their stems, so that when the stalk 

 breaks away from its attachment, the 

 scar and the micropyle come close to- 

 gether at one end, as in the squash seed. 



Make a drawing of the outside of a 

 seed, labeling all the parts you have observed ; then gently 



in 



FIG. 26. Diagram of 

 an inverted or anatro- 

 pous seed, showing the 

 parts in section : a, outer 

 coat ; b, inner coat ; c, 

 kernel ; d, rhaphe ; ch, 

 chalaza ; h, hilum ; m, 

 micropyle (After GRAY). 



V / 



