VARIATIONS, DUE TO REVERSION. 59 



their heads ; and the presence of teeth, which never 

 cut through the gums, in the upper jaws of our un- 

 born calves. It has even been stated, on good author- 

 ity, that rudiments of teeth can be detected in the 

 beaks of certain embryonic birds. Nothing can be 

 plainer than that wings are formed for flight; yet in 

 how many insects do we see wings so reduced in size 

 as to be utterly incapable of flight, and not rarely lying 

 under wing-cases, firmly soldered together ! The mean- 

 ing of rudimentary organs is often quite unmistakable ; 

 for instance, there are beetles of the same genus (and 

 even of the same species) resembling each other most 

 closely in all respects, one of which will have full- 

 sized wings, and another mere rudiments of mem- 

 brane; and here it is impossible to doubt that the 

 rudiments represent wings. * * * In plants of 

 the same species, the petals sometimes occur as mere 

 rudiments, and sometimes, in a well-developed state. 

 In some plants with their sexes separated, the male 

 flowers include a rudiment of a pistil." 



When these animals and plants are placed under 

 domestication, or cultivated, the rudimentary organs 

 which " relate to a former condition," become re-devel- 

 oped ; and then Darwin proceeds to calculate, thus for 

 instance : If this beetle (say) has developed a pair of 

 wings, within one year, is it not probable that, at the 

 same rate of variation, it may develop into an eagle, in 

 the course of the next million years ? 



" Rudimentaiy organs may be utterly aborted," * * 

 with "no trace left" (p. 533, Origin of Species). 



Darwin adduces variations, or improvements, under 

 domestication, to prove how transitions from lower to 

 higher specific forms may be made, and have been 

 made ; but, in the very exposition of his problem, he 



