CHAP. VII.] THEORY OF NATURAL SELECTION. 163 



entre le pericarpe et le placenta." In the flowers of Saponaria 

 officinalis, Dr. Masters has observed instances of both marginal 

 and free central placentation. Lastly, St. Hilaire found towards 

 the southern extreme of the range of Gomphia oleseformis two 

 forms which he did not at first doubt were distinct species, but h\ 

 subsequently saw them growing on the same bush ; and he then 

 adds, " Voilk done dans un meme individu des loges et un style 

 qui se rattachent tantot a un axe verticals et tantot a un 

 gynobase." 



We 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 selection. 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 pro- 

 nounced variations, that the plants have been caught in the act of 

 progressing towards a higher state of development ? On the con- 

 trary, I should infer from the mere fact of the parts in question 

 differing or varying greatly on the same plant, that such modifica- 

 tions were of extremely small importance to the plants themselves, 

 of whatever importance they may generally be to us for our 

 classifications. The acquisition of a useless part can hardly 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 invoked, 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 uniformly for a length of time, we may infer that the result 

 would be almost uniform ; and in this case all the individuals of 

 the species would be modified in the same manner. 



From the fact of the above characters being unimportant for 

 the welfare of the species, any slight variations which occurred in 

 them would not have been accumulated and augmented through 

 natural selection. A structure which has been developed through 

 long-continued selection, when it ceases to be of service to a 

 species, generally becomes variable, as we see with rudimentary 

 organs ; for it will no longer be regulated by this same power of 

 selection. But when, from the nature of the organism and of the 

 conditions, modifications have been induced which are unim- 

 portant for the welfare of the species, they may be, and apparently 

 often have been, transmitted in nearly the same state to numerous, 

 otherwise modified, descendants. It cannot have been of much 

 importance to the greater number of mammals, birds, or reptiles, 

 whether they were clothed with hair, feathers, or scales ; yet hair 

 has been transmitted to almost all mammals, feathers to all birds, 

 and scales to all true reptiles. A structure, whatever it may be, 



