THE SPRUCE FIR 



279 



remains undivided, and has nothing to do directly with 

 the development of the young plant. It only serves 

 as a store of food for the embryo. 



Fio. 114. ^4, Ovum at the time of fertilisation : p, end of 

 pollen-tube ; sn, generative nucleus from the pollen- 

 tube ; on, nucleus of ovum. B, Ovum a little later : the 

 two nuclei are in the act of fusing. O, Base of ovum 

 showing first divisions after fertilisation : two of the 

 four cells are shown. D, More advanced stage : four of 

 the eight cells are shown. E, Still more advanced stage : 

 8, cells from which suspensor will be formed ; e, cells of 

 the embryo. F, Still later stage : the suspensor s has 

 grown to a great length (it is composed of four cells). 

 The rudimentary embryo, e, has been pushed downward 

 by the growth of the suspensor. Magnified about 70 

 diameters. (After Strasburger. ) 



