284 



PLANT LIFE. 



to traverse the pistil. Pollen tubes may, therefore, grow 

 10-15 cm. in length. Usually the older \y\\\. of the tube dies 



Fig. 320. — Anterior fcmrth of female gametophyte of spruce {Piccn crcelsa), showing 

 two ovaries, e, tissue of gametopliyte (endosperm); -?, egg; k. nucleus of egg; h, 

 neck of ovary (the line docs not reach the neck, which is situated in a depression of the 

 plant below h ; the sliading shows the side of this slope); /cz, neck canal cell. See fig. 

 321. Magnified 50 diam. — After Strasburger. 



Fig. 321. — A portion of the o\'ary of the spruce, seen as in lig. 321.', but magnified I'Ss 

 diam. The cell kz of fig, 320 has become disorganized to make way for the pollen 

 tube,/, which has pushed between the neck celts and readied the egg, c, into wliich 

 one of the sperms in its tip is about to enter. g\ tissue of the female gametophyte. — 

 After Strasburger, 



Fig. 322. -Upper part of ovule of red cedar, with iiUegunient remo\'ed, >!n, mega- 

 sporangium ; al, female gametophyte with three (i\aries nt ,i cluster of si.v ; /, pollen 

 tube. Each ovary shows an elongated egg and al.i()\e the small neck cells. The left- 

 hand pollen tube has two sperms about to pass between neck cells into an egg. Magni- 

 fied 67 diam,— After Strasburger, 



as the ti[) ad\-ances. The tbod needed is ehielly derived 

 from the cells of the stii^ma and st\'le which iL disorganizes. 



