2(34 THE ORIGIN OF SPECIES 



may hope hereafter to see the law proved true. It can, 

 however, be proved true only in those cases iu which 

 the ancient state of the progenitor of the group has not 

 been wholly obliterated, either by successive variations 

 having supervened at a very early period of growth, or 

 by such variations having been inherited at an earlier age 

 than that at which they first appeared. It should also be 

 borne in mind that the law may be true, but yet, owing 

 to the geological record not extending far enough back 

 in time, may remain for a long period, or forever, in- 

 capable of demonstration. The law will not strictly hold 

 good in those cases in which an ancient form became 

 adapted in its larvae state to some special line of life, 

 and transmitted the same larval state to a whole group 

 of descendants; for such larval will not resemble any still 

 more ancient form in its adult state. 



Thus, as it seems to me, the leading facts in em- 

 bryology, which are second to none in importance, are 

 explained on the principle of variations in the many 

 descendants from some one ancient progenitor having 

 appeared at a not very early period of life, and hav- 

 ing been inherited at a corresponding period. Embry- 

 ology rises greatly in interest, when we look at the 

 embryo as a picture, more or less obscured, of the pro- 

 genitor, either in its adult or larval state, of all the 

 members of the same great class. 



Rudimentary, Atrophied, and Aborted Organs 



Organs or parts in this strange condition, bearing the 

 plain stamp of inutility, are extremely common, or even 

 general, throughout nature. It would be impossible to 



