210 BOTANY OF THE LIVING PLANT 



Heaths, or Orobancheae, rather than in those held to be primitive. 

 All these facts taken together lead to the conclusion that irregular 

 nutrition among Flowering Plants is secondary. Its methods have 

 been adopted individually, and comparatively late in Descent, by 

 organisms of which the ancestry were autophytes. Moreover it has 

 not started along any single line of Descent, but along many. In 

 this, as in so many special adaptations, homoplasy, or parallel develop- 

 ment is frequently illustrated. The advance has been along lines of 

 opportunism. Close crowding has encouraged it. Use has been made 

 of such circumstances as offered in order to achieve the end of the 

 plants' existence. That end is not merely the maintenance of the 

 individual, but the propagation of the race by new germs. The case of 

 Rafflesia illustrates this in a striking though extreme manner. (Figs. 

 145, 146.) Its vegetative system is reduced in accordance with its 

 parasitism, to the level of fungal hyphae. But its flower is of 

 enormous size, complex in structure, and results in a great output 

 of seeds, each containing a new germ {ovula numerossisima, as 

 Robert Brown called them). The nutritive system though 

 reduced, is still effective for nourishing this flower. Thus the 

 propagation of the race takes precedence over the vegetative 

 development. This is the ultimate lesson taught by the study 

 of irregular nutrition, and by the morphological degradation 

 of the vegetative system, which so often follows on its successful 

 practice. Propagation is the real end. Vegetative development is only 

 a means to that end. The whole vegetative system may be regarded 

 as a physiological scaffold, while the mechanism of propagation is 

 the substantive building which is erected by means of it. 



