TRUE NATURE OF FLORAL ORGANS. th7 
through the style (if there is one), there are found long cells 
sometimes with intermediate spaces, through which latter the 
pollen tubes readily find their way (Fig. 141). When no such 
intercellular spaces exist, the pollen tube proceeds through 
the cell walls, which it softens by means of a substance which 
it exudes for that purpose. 
192. Structure of the Ovule.— The details of the micro- 
scopic anatomy of the ovule are rather complicated. It is 
enough for our present purpose to state that the young ovule, 
_ before it has begun to form an embryo, usually exists as a 
roundish or egg-shaped mass, with a small opening leading 
into its apex. This opening leads to a sac inside the ovule, 
filled with soft protoplasmic material, containing cells and 
known as the embryo sac. Minute cells occur at the apex 
of the ovule (Fig. 142), and it is from their growth and 
development that the embryo is at length produced. 
