90 SCIENCE PRIMERS. [xxii. 



XXII. THE SEED. 

 TESTA, ALBUMEN, EMBRYO. 



130. The seed consists of the embryo (Par. 35) 

 and its coverings (integuments), and sometimes 

 albumen ; it is the ovule fertilized and arrived at 

 maturity, at which period it has become independent 

 of the parent plant ; it is attached to the pericarp by 

 a short or long cord, funicle (Par. no), through 

 which it derived nourishment from the parent. 



131. The integuments are usually double, the two 

 coverings sometimes corresponding to the two coats 

 of the ovule (Par. 114); the outer (testa) is generally 

 the harder and thicker, and is sometimes, but very 

 rarely, juicy (pomegranate). Two points should be 

 carefully noted on the testa the scar (hilum) 

 indicating its point of attachment, and a minute 

 hole (micropyle) by which the pollen-tube entered 

 the ovule (Par. 114). The radicle of the embryo 

 almost always points to this hole. In some seeds 

 a ridge (raphe) passes from the funicle to the 

 opposite end of the seed, indicating the position of 

 the nourishing vessels that go to the base of the 

 nucleus (Par. 114), where they sometimes expand into 

 a dark spot. In many palm seeds the raphe sends 

 branches of vascular bundles through the testa. 



132. The embryo is a rudimentary plant (Par. 35) 

 with partially-developed organs. The radicle of the 

 embryo is developed first, and is hence to be found 

 next the micropyle (Par. 131). When fully formed the 



