Origin of Species Variorum

Comparison with 1860

far enough back in time, may remain for a long period, or for ever, incapable of demonstration. ↑

Thus, as it seems to me, the leading facts in embryology, which are second in importance to none in natural history, are explained on the principle of slight modifi- cations not appearing, in the many descendants from some one ancient progenitor, at a very early period in the life of each, though perhaps caused at the earliest, and being inherited at a corresponding not early period. Embryology rises greatly in interest, when we thus look at the embryo as a picture, more or less obscured, of the common parent-form of each great class of animals.

Rudimentary , atrophied , or aborted Organs — .

Organs or parts in this strange condition, bearing the stamp of inutility, are extremely common throughout nature. ↑ For instance, rudimentary mammæ are very general in the males of mammals: I presume that the "bastard-wing" in birds may be safely considered as a digit in a rudimentary state: in very many snakes one lobe of the lungs is rudimentary; in other snakes there are rudiments of the pelvis and hind limbs. Some of the cases of rudimentary organs are extremely curious; for instance, the presence of teeth in fœtal whales, which when grown up have not a tooth in their heads; and the presence of teeth, which never cut through the

far enough back in time, may remain for a long period, or for ever, in- capable of demonstration. The law will not hold good in those cases in which an ancient form became adapted in its larval state to some special line of life, and transmitted the same larval state to a whole group of descendants; for these in their larval condition will not resemble any ancient form in its adult state.

Thus, as it seems to me, the leading facts in embryology, which are second .. to none in importance, are explained on the principle of modifications in the many descendants from some one ancient progenitor, not having appeared at an early period of life, and having been inherited at a corresponding .. period. Embryology rises greatly in interest, when we .. look at the embryo as a picture, more or less obscured, of the progenitor, 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 difficult to name one of the higher animals in which some part is not in a rudimentary condition. ↑ In the mammalia, for instance, the males always possess rudimentary mammæ; in snakes one lobe of the lungs is rudimentary; in birds the "bastard-wing" may safely be considered as a rudimentary digit, and in not a few species the wings cannot be used for flight or are reduced to a rudiment. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. What can be more curious than the presence of teeth in fœtal whales, which when grown up have not a tooth in their heads; or the .. teeth, which never cut through the