ON THE ORIGIN OF GENERA. 107 



or its ultimate type, can be only ascribed as yet to the divine fiat. 

 So far as we can see, there is no reason or law to produce a prefer- 

 ence for this direction above any other direction. 



If from these fixed bases descendants have attained to succes- 

 sive stations on the same line of progress, in subordinate features 

 of the nervous and circulatory systems, constituting the "syn- 

 thetic " predecessors of the orders in each class, the type finally 

 reached seems to rest on no other basis than the pleasiire of the 

 Almighty. 



(3. As affecting Family Characters. 



If from the single species generalizing a modern order we at- 

 tempt to deduce synthetic predecessors of existing families, we 

 find some difficulty, if we attempt to see in these stages a uniform 

 succession of progress. A suppression of some features, and ad- 

 vance in others, in one and the same individual up to the period 

 of reproduction, would produce ofl'spring divergent from the start, 

 and represent the relationship of families as we find them. 



y. As affecting Generic Characters. 



If the extremes of our series of genera were characterized by 

 structures particularly adapting them above all others to some 

 contemporary necessity of existence, this second law, or Darwin's, 

 might be regarded as primary. But the writer's experience of 

 comparative anatomy has led him to believe that this is not the 

 case, as expressed in Proposition IV, page 91. 



This view had not been overlooked by Darwin, who, however, 

 treats of it very briefly, and apj)ears to attach it to the theory 

 of adaptations, or modifications for a physiological purpose. He 

 says, "Origin of Species," page 388 (Amer. edit, 1860): "We 

 may extend this view to whole families, or even classes. The 

 fore-limbs, which served as legs in the parent siaecies, may become, 

 by a long course of modification, adapted in one descendant to 

 act as hands, in another as paddles, in another as wings ; and on 

 the above two principles — namely, of each successive modification 

 supervening at a rather later age, and being inherited at a corre- 

 Fpondingly late age — the fore-limbs in the embryos of the several 

 descendants of the parent species will still resemble each other 

 closely, for they will not have been modified. But in each indi- 

 vidual new species the embryonic fore-limbs will differ greatly 

 from the fore-limbs in the mature animal ; the limbs in the latter 

 have undergone much modification at a rather late period of life. 



