WHAT IS A SEED? 



91 



stalk is called, in all seeds, the funiculus. When 

 the funiculus breaks away from the seed, it 



leaves a scar (D, 

 Fig. 88) . This scar 

 is the hilum. 



118. If we split 

 the bean length- 

 wise (preferably 

 after it has been 

 soaked in water 

 for a few hours), 

 we find that the 

 seed is composed of 

 two thick cotyledons ; 

 and these are the 

 parts which are 

 afterwards elevated 

 into the air (a, Fig. 86). One-half of a bean 

 (that is, one cotyledon) is shown in Fig. 88. The 

 other cotyledon was attached at C. The plumule 

 is at S, and the incipient stem, or caulicle, at 

 O. All these parts cotyledons, caulicle, plumule, 

 constitute the embryo. 



118a. Over the point of the caulicle, the close observer will 

 find a minute depression and a hole leading into the bean. This 

 is the micropyle, and is the point at which the pollen-tube en- 

 tered, and the place through which the root breaks in germination. 

 In the cocoa-nut the positions of the three micropyles are shown 

 by the scars (Fig. 89), but since only one of the locules develops 

 a seed, germination takes place through only one place. 



FIG. 89. 

 Micropylar scars of cocoa-nut. 



