332 ELEMENTARY BIOLOGY 



still further contribution of each generation to the next in the 

 form of special structures or organs that assist the young plant 

 in getting to some distance from the parent (see pp. 315-319). 



386. Advantage of longer infancy to the species. In all 

 these various directions the organisms expend energy in ways 

 that enable the offspring to get a better start in life than would 

 be possible if the spore or the gamete (or zygote) were dis- 

 charged by the parent immediately upon being formed. On com- 

 paring the various groups of plants with respect to the amount 

 of nourishment or protection that parents supply to the young, 

 or with respect to any other services rendered by the parents to 

 the young, we shall see that with the ascent of plant life from 

 the lowest to the highest there is an increase of the dependence 

 of the offspring upon the parent. And with the increase of 

 service rendered by parents to offspring there is at the same 

 time an increased advantage to the species. 



An advance in the scale of life seems to impose additional 

 burdens upon the organisms. But these are more than com- 

 pensated by the additional advantages. As has already been 

 pointed out, the production of flowers and fruits and seeds is 

 a source of great expense in material and energy to the organ- 

 ism. Yet in any species of plants that produces well-stored 

 seeds, well-protected seeds, and seeds well adapted to wide 

 dispersal every individual gets the full benefit of this addi- 

 tional expc7iditnre of energy at the very beginning of his career. 

 We might even say that, apart from all other considerations, a 

 plant comes to be able to do all of its life's work just in pro- 

 portion as its parent has guarded its youth and has given it a 

 good start. In doing things for posterity a plant is thus merely 

 repaying to the species what was done for it in the past. 



Of course we are not to suppose that the plants do this or that 

 because they have any feeling of gratitude, or ability to foresee future 

 needs. In speaking of the advantages or disadvantages of various 

 types of behavior on the part of plants, we mean merely to point out 

 that certain kinds of doings may actually contribute to the prosperity 



