66 PLANT LIFE. 



zygospore. In these examples the greater part of the 

 protoplasm is used up in the formation of the reproductive 

 bodies ; but as differentiation in this direction proceeds, we 

 observe that the relative bulk of the individual specialized 

 for reproductive purposes becomes less and less, until 

 we reach Phanerogams, where the parts concerned in 

 the process, stamens and ovules, or young unfertilized 

 seeds, usually bear a very small proportion to the whole ; 

 and yet in the fertilized seed we get a concentration of all 

 that is required to evolve, under favourable conditions, into 

 an individual like the parent form. This concentration of 

 the energy of an individual into a small portion — a seed — for 

 reproductive purposes, admits of the remainder, which 

 usually constitutes the bulk of a fully-grown individual, 

 being sooner or later returned in the form of dead organic 

 matter, that eventually resolves itself during the process of 

 decay into those same inorganic compounds that were 

 utilized for the building up of its own structure, and retained, 

 so long as life was the dominant force over the mass. 

 After complete disintegration the same material is available 

 for use over again by some other living plant ; thus it is seen 

 that the evolution of sex, and concentration of the repro- 

 ductive ' portions into a small compass, has furnished an 

 endless supply of material available for plant food, by utiliz- 

 ing the same material over and over again. The cycle of 

 movement of inorganic matter suitable for plant food may 

 be varied ; for instance, a given plant that has built itself up, 

 or in other words that has fashioned so much inorganic 

 matter into a living tree, eventually dies, and sooner or later 

 its wood, leaves, etc., become broken up into gases, water, 

 and salts ; that is, other forces now dominant over the dead 

 tree are undoing what life while dominant did for the tree. 



