THEORY OF NATURAL ISELECTION. 207 



Helianthemum the capsule has been described as uiiilocu- 

 lar or tri-locular; and in H. mutabile, " Une hime plus on 

 moins large, s'etend entre le pericarpe et le placenta." In 

 the flowers of Saponaria officinalis Dr. Masters lias 

 observed instances of both marginal and free central plac- 

 entation. Lastly, St. Hilaire found toward the southern 

 extreme of the range of Gomphia oleseformis two forms 

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

 he subsequently saw them growing on tlie same bush; and 

 he then adds, " Voila done dans un rneme indivielu des 

 loges et un style qui se rattaclient tantot a un axe verticale 

 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 tend- 

 ency toward 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 progressiug 

 toward a higher state of development? On the contrary, 

 I should infer from the mere fact of the parts in questioi 

 differing or varying greatly on the same plant, that such 

 modifications were of extremely small importance to the 

 i:)lants themselves, of whatever importance they may gener- 

 ally 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 tlian 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 unimpor- 

 tant for the welfare of the species, any slight vai-iations 

 which occurred in them would not have been accumulated 

 and augmented through natural selection. A structure 

 which has been developed througli long-continued selec- 

 tion, when it ceases to be of service to a species, generally 



