Chap. IX CONCLUDING KEMAKKS. 285 



which had their ovaria less and less twisted, but if 

 the plant only afforded varieties with the ovarium 

 more twisted, the same end could be attained by the 

 selection of such variations, until the flower w^as 

 turned completely round on its axis. This seems to 

 have actually occurred with Malaxis paludosa, for 

 the labellum has acquired its present upward posi- 

 tion by the ovarium being twisted twice as much as 

 is usual. 



Again, we have seen that in most Vandese there is 

 a plain relation between the depth of the stigmatic 

 chamber and the length of the pedicel, by which the 

 pollen-masses are inserted ; now if the chamber became 

 slightly less deep from any change in the form of the 

 column or other unknown cause, the mere shortening 

 of the pedicel would be the simplest corresponding 

 change ; but if the pedicel did not happen to vary in 

 shortness, the slightest tendency to its becoming bowed 

 from elasticity as in Phalaenopsis, or to a backward 

 hygrometric movement as in one of the Maxillarias, 

 would be preserved, and the tendency would be con- 

 tinually augmented by selection ; thus the pedicel, as 

 far as its action is concerned, would be modified in 

 the same manner as if thad been shortened. Such 

 processes carried on during many thousand generations 

 in various ways, w^ould create an endless diversity of 

 co-adapted structures in the several parts of the flower 

 for the same general purpose. This view affords, I 

 believe, the key which partly solves the problem of the 

 vast diversity of structure adapted for closely analogous 

 ends in many large groups of organic beings. 



The more I study nature, the more I become 

 impressed with ever-increasing force, that the con- 

 trivances and beautiful adaptations slowly acquired 

 through each part occasionally varying in a slight 



