EXPERIMENTS WITH PLANTS 



even with the naked eye : these develop into foliage 

 leaves. The seed-leaves, caulicle and plumule together, 

 make up the germ or embryo plant. The seed of the 

 Horse-bean, therefore, consists of an embryo plant 

 provided with a cover. 



THE CASTOR- BEAN. 1 The seed somewhat resembles 

 a beetle in shape and color. Its scar (hilum) is covered 



3. Castor-bean; at (ca) the car- 

 uncle, a spongy body which 

 absorbs water during ger- 

 mination; the scar (hilum) 

 is concealed by it. 



4. Castor-bean opened, showing 

 endosperm (e), caulicle (c). 

 seed-leaves (si) and caruncle 

 (ca). 



by a spongy body (the caruncle, Fig. 3, ca) . The cover 

 has a very different texture from that of the Horse- 

 bean cover and fits loosely. The seed-leaves (Fig. 4) 

 are thin and delicate in appearance, with prominent 

 veins ; the caulicle and plumule are much smaller than 

 in the Horse-bean. Outside the seed-leaves is a 

 white oily substance which surrounds the germ but is 

 not attached to it: it is called endosperm (Fig. 4, e) . 

 THE CORN. Both dry and soaked grains should be 

 used. In the Corn (Fig. 5) the seed-case adheres to 

 the seed and forms the outer layer of the seed -cover, 



1 This is poisonous and should not be eaten. 



