Chap. VII.] THEORY OF NATURAL SELECTION. 273 



se rattachent tantot a un axe verticale et tantot a un 

 gynobase." 



AVe thus see that with plants many morphological 

 changes may be attributed to the laws of growth and 

 the inter-action of parts, independently of natural selec- 

 tion. But with respect to Nageli's doctrine of an innate 

 tendency towards perfection or progressive development, 

 can it be said in the case of these strongly pronounced 

 variations, that the plants have been caught in the act 

 of progressing towards a higher state of development? 

 On the contrary, I should infer from the mere fact of 

 the parts in question differing or varying greatly on the 

 same plant, that such modifications were of extremely 

 small importance to the plants themselves, of whatever 

 importance they may generally be to us for our classi- 

 fications. The acquisition of a useless part can hard- 

 ly be said to raise an organism in the natural scale; 

 and in the case of the imperfect, closed flowers 

 above described, if any new principle has to be in- 

 voked, it must be one of retrogression rather than of 

 progression; and so it must be with many parasitic 

 and degraded animals. We are ignorant of the 

 exciting cause of the above specified modifications-; 

 but if the unknown cause were to act almost uniform- 

 ly for a length of time, we may infer that the result 

 would be almost uniform; and in this case all the in- 

 dividuals of the species would be modified in the same 

 manner. 



From the fact of the above characters being unim- 

 portant for the welfare of the species, any slight varia- 

 tions which occurred in them would not have been ac- 

 cumulated and augmented through natural selection. 

 A structure which has been developed through long- 



