348 Darwin, and after Darwin. 



four dififerent lines of descent — namely, the insects, 

 reptiles, birds, and mammals. Now if in all, or in- 

 deed in any, of these four cases the wings had been 

 developed on the same anatomical pattern, so as not 

 only to present the analogical resemblance which it is 

 necessary that they should present in order to dis- 

 charge their common function of flying, but likewise 

 an homologous or structural resemblance, showing 

 that they had been formed on the same anatomical 

 " plan/' — if such has been the case, I say, the theory 

 of natural selection would certainly be destroyed. 



Now it has been alleged by competent naturalists 

 that there are several such cases in organic nature. 

 We have already noticed in a previous chapter 

 (pp. 58, 59), that Mr. Mivart has instanced the eye 

 of the cuttle-fish as not only analogous to, but also 

 homologous with, the eye of a true fish — that is to 

 say, the eye of a mollusk with the eye of a vertebrate. 

 And he has also instanced the remarkable resemblance 

 of a shrew to a mouse — that is, of an insectivorous 

 mammal to a rodent — not to mention other cases. 

 In the chapter alluded to these instances of homo- 

 logy, alleged to occur in difterent branches of the tree 

 of life, were considered with reference to the process 

 of organic evolution as a fact : they are now being 

 considered with reference to the agency of natural 

 selection as a method. And just as in the former 

 case it was shown, that if any such alleged instances 

 could be proved;, the proof would be fatal to the 

 general theory of organic evolulion by physical 

 causes, so in the present case, if this could be 

 proved, it would be equally fatal to the mere spe- 

 cial theory of natural selection. But, as we have 



