THE SEED. 305 



CHAPTER VIIL 



THE SEED. 



587. THE SEED is the fertilized ovule (515), with embryo 

 formed within it. It consists, like the ovule, of a nucleus or 

 kernel, enclosed by integuments. The seed-coats are those of 

 the ovule, viz. two, or sometimes only one, in certain plants 

 none. Occasionally an accessory coat appears after fertiliza- 

 tion ; and certain appendages may be produced, as outgrowths 

 from some part of its surface or from its base. The nucleus or 

 kernel is composed either of the embryo alone, or of a nutritive 

 deposit in addition. (19-41.) All the parts of a seed are in- 

 dicated in Fig. 663. 



588. The SEED-STALK or PODOSPERM, when there is one, is 

 the funiculus of the ovule (516), and retains this name. So 

 also do the CHALAZA, RHAPHE, and HILUM ; the latter being the 

 scar left by the separation of the seed from 



its funiculus or directly from the placenta. 

 The foramen of the ovule, now closed, is 

 the MICROPYLE of the seed. 



589. The terms which denote the char- 

 acter of the ovule, such as orthotropous, 



campylotropous, amphitropous, and anatropous, apply equally to 

 the resulting seed. 



590. Seed-Coats. The integuments of the seed answer to the 

 primine and secundine of the ovule. The main seed-coat is the 

 exterior integument of the ovule when there is more than one. 

 Being the most firm coat, and not rarely crustaceous in texture, 

 it takes the name of TESTA, which is equivalent to seed-shell. 

 It has also been named SPEKMODERM (seed-skin) , and sometimes 

 Episperm. The latter name (meaning upon the seed) is best 

 applied to the pellicle or outer layer, sometimes a thick one, 

 which the testa of certain seeds forms. The testa is extremely 

 various in form and texture, is either close and conformed to 



FIG. 663. Vertical magnified section of the (anatropous) seed of the American Lin- 

 den; with the parts indicated, viz. the hilum (a); testa (6); tegmen (c); albumen (d); 

 embryo (e). 664. Vertical section of the orthotropous seed of Helianthemum Cana- 

 dense, with its funiculus, a. 



