CHAP. XV.] RECAPITULATION. 379 



though distinct species, though fitted in the adult state for habits 

 as different as is possible. Larvae are active embryos, which have 

 been specially modified in a greater or less degree in relation to 

 their habits of life, with their modifications inherited at a corre- 

 sponding early age. On these same principles, and bearing in 

 mind that when organs are reduced in size, either from disuse or 

 through natural selection, it will generally be at that period of life 

 when the being has to provide for its own wants, and bearing in 

 mind how strong is the force of inheritance the occurrence of 

 rudimentary organs might even have been anticipated. The im- 

 portance of embryological characters and of rudimentary organs in 

 classification is intelligible, on the view that a natural arrangement 

 must be genealogical. 



Finally, the several classes of facts which have been considered 

 in this chapter, seem to me to proclaim so plainly, that the innu- 

 merable species, genera and families, with which this world is 

 peopled, are all descended, each within its own class or group, 

 from common parents, and have all been modified in the course of 

 descent, that I should without hesitation adopt this view, even if 

 it were unsupported by other facts or arguments. 



CHAPTER XV. 

 RECAPITULATION AND CONCLUSION. 



Recapitulation of the objections to the theory of Natural Selection Recapitu- 

 lation of the general and special circumstances in its favour Causes of 

 the general belief in the immutability of species How far the theory of 

 Natural Selection may be extended -Effects of its adoption on the study 

 of Natural History Concluding remarks. 



As this whole volume is one long argument, it may be convenient 

 to the reader to have the leading facts and inferences briefly re- 

 el] >itulated. 



That many and serious objections may be advanced against the 

 theory of descent with modification through variation and natural 

 selection, I do not deny. I have endeavoured to give to them 

 their full force. Nothing at first can appear more difficult to 

 believe than that the more complex organs and instincts have been 

 perfected, not by means superior to, though analogous with, 

 Imman reason, but by the accumulation of innumerable slight 

 variations, each good for the individual possessor. Nevertheless, 

 this difficulty, though appearing to our imagination insuperably 

 great, cannot be considered real if we admit the following pro] o 



