SEXUALITY AND THE ENVIRONMENT. 231 



of a plant, then eitlier of the sexual organs mav begin 

 to deterioriate, till they become metamorphosed into petals 

 or leaves, or else degenerate and vanish. 



It is true enough that we know nothing of the real nature 

 of life ; but it is easy to see that, of the various phases of 

 development, from germination to the production of seed, 

 each should have the proper amount of energy at its disposal, 

 and no more ; for if any one organ be stimulated beyond the 

 optimum degree, others suffer through atrophy. The first 

 and well-known distinction to be noticed lies, of course, 

 between the " vegetative energy," by means of which 

 roots, stems, branches, and foliage are developed, and the 

 "reproductive energy," which brings about the formation of 

 flowers, fruit, and seed. If either of these be unduly excited, 

 the other diminishes. Thus, as long as fruit trees are 

 developing much Avood and foliage, they either bear fruit 

 badly or not at all. Plants which are propagated largely 

 by vegetative means of multiplication, such as bulbs, corms, 

 tubers, etc., are notorious for failing to set seed as well. As 

 an instance in nature, Ranunculus Ficaria may be mentioned. 

 This plant propagates itself by " root-tubers " and by aerial 

 corms, and rarely produces much fruit, for the pollen often 

 remains in an arrested state.* Conversely, if vegetative 

 energy be checked by root and branch pruning, bark-ringing, 

 etc., the reproductive energy is promoted, and an abundance 

 of fruit is the reward. Similar results follow a decrease of 

 energy through impoverishment, when enormous crops of 

 fruit may be borne by trees, as I have seen in Portugal 

 Laurels, when the roots had penetrated a bed of gravel and 

 the branches became decayed. 



Apart from these general considerations certain special 

 conditions are found to favour one sex more than the other, 

 * See Van Tieghem on R. Ficaria, Ann. des Sci. Nat., v., ser. 5, p. 88. 



