382 SCOTS PINE. 



the coat, treat the endosperm of one seed with potash to 

 make it transparent, and place that of another in water 

 and tease out with needles the numerous embryos which 

 are embedded in the endosperm in a central cavity. 

 Longitudinal sections should also be cut of the endosperm, 

 to see the embryos in situ. Note the cylindrical or club- 

 shaped embryos, each carried at the end of a twisted 

 suspensor consisting of thin-walled transparent cells. In 

 the largest embryo in each seed, note the parts named 

 in the next paragraph (radicle, hypocotyl, cotyledons, 

 plumule) . 



534. Structure of Seed. Examine ripe seeds, and 

 note : 



(1) The wing is readily detached from the seed itself. 



(2) The thick and hard seed-coat. 



(3) The micropyle at one end demonstrated by 

 dipping the dry seed into hot water. 



(4) The endosperm, seen on removal of the seed-coat 

 test for starch, proteids, oils, and also examine sections 

 with microscope, noting results. 



(5) The membranous layer, usually reddish, covering the 

 endosperm and representing the remains of the nucellus. 



(6) The embryo, lying in an axial cavity in the 

 endosperm, and having a long hypocotyl. This merges 

 into the radicle at the micropyle end of the seed and at 

 the other end bears a circle of narrow cotyledons about 

 six in Scots Pine surrounding the small plumule. Cut 

 soaked seeds open, some longitudinally and others trans- 

 versely, and note that in most cases there is attached to 

 the radicle a string- like suspensor greatly coiled up ; in 

 some seeds several suspensor s may be found, each with an 

 embryo at its free end the end farthest from the 

 micropyle. 



535. Germination of Seed. Sow soaked seeds, and 

 note the stages in germination: (1) the coat bursts, 

 owing to swelling of endosperm and embryo ; (2) the 

 radicle grows out and curves downwards ; (3) the 

 hypocotyl elongates, carrying up the seed; (4) the 



