CHAPTER XIV. THE SPERMAPHYTA. 



371 



gives rise to a pollen-tube. The female flower is a cone borne 

 at the apex of a small branch. Each fertile scale bears on either 

 side of a central rib, near its base, two ovules, whose micropyles 

 point obliquely downward. The ovule-bearing scale is in the 

 axil of a bract, and slightly attached to it at the base. Each 

 ovule consists of a nucellus enclosed in a single coat, as is most 



Fig. 571. Pinus sylvestris. A, female cone somewhat enlarged ; B, one of the fruit- 

 ing scales considerably magnified, showing upper surface and two ovules near its base, 

 pointing obliquely downward. The bract, in the axil of which the fruiting-scale is borne, is 

 concealed behind the latter. C, diagram of upper part of ovule much magnified ; a, coat 

 of ovule ; m, micropyle ; p, pollen-grain sending tube into nucellus, n ; b, embryo-sac filled 

 with endosperm : c, one of the two archegonia. D, scale with ripened seeds ; these each 

 possess a prominent wing. E, seed with wing removed and cut longitudinally to show albu- 

 men and embryo. 



commonly the case in Gymnosperms. When the ripened pollen- 

 sacs begin to open to shed their pollen, the axis of the fertile 

 cone lengthens so as to separate the scales and permit the access 

 of the pollen. The latter, conveyed by the wind and falling 

 upon the ovule-bearing scale, slips down it to the base, being 

 guided in its course partly by the projecting mid-rib, partly by 

 the peculiar formation of the scale, and partly by the append- 

 ages of the pollen-grains, until they rest in the micropyles of the 

 ovules. The pollination thus accomplished, the scales of the 

 cone close together at the top, and become agglutinated with 

 resinous matter. At the time this takes place the ovule is very 



