Reproduction and Germination. 



41 



A number of internodes which have attained but a fraction 

 of their final length may be distinguished near the apex of the 

 stem. What is the fate of the endosperm? (See " Nutrition 

 and metabolism.") 



35. Germination of seeds of Ricinus.— Soak some 

 seeds of the castor-oil plant {Ricinus) in water for a day, then 

 place in moist sawdust or soil. Dissect one of the swelling 

 seeds, and note the form and consistency of the thin, white 

 cotyledons, and the endosperm filled with fatty and proteid re- 



!,■■ .ah 



I ah 



B 



G 



Fig. 21. — Germination of seeds of Ricinus (A), Asparagus (B), and Pisum (C). ig^ 

 integuments ; r, main root ; pa., root-hairs ; ah^ hypocotyledonary axis ; z, z, pc, 

 insertion of cotyledons ; /, stem ; a, endosperm. After Bonnier and Leclerc du 

 Sablon. 



serve material. Make out the manner in which the cotyledons 

 are inserted on the short hypocotyl, and also the apical por- 

 tion of the young root. 



Follow the course of the embryo by daily dissections, noting 

 the development of the root, change in the endosperm, the 

 origin of the root-hairs and of the secondary roots. Examine 

 curved portions of the main root, and ascertain whether the 

 secondary roots arise on the concave or convex surfaces of the 

 curved portion. Follow the growth of the hypocotyl, measure 



