EVOLUTION AND ITS CONSEQUENCES. H 



reasouiug, requires me to believe that the groups of species, that 

 is, groups A and B, are also derived from commou parents, and 

 the more advanced have been accelerated or the less advanced re- 

 tarded, as the case may have been with regard to the parents. 



This is not an imaginary case, but a true representation of 

 many cases which have come under notice. I can not repeat 

 them here, but refer to the original memoirs, where they may be 

 found. * 



This is a simple statement of the law of '^ acceleration and re- 

 tardation " of some American naturalists, which probably expresses 

 better than any other the ^^ manner of evolution," the proposition 

 with which we started. 



Hyatt thus defines it as seen in a group of ammonites which 

 he studied : " The young of higher species are thus constantly 

 accelerating their development, and reducing to a more and more 

 embryonic condition the stages of growth corresponding to the 

 adult periods of preceding or lower species." f 



This form of demonstration of evolution is of far wider appli- 

 cation than that which I first brought forward. X Iii the latter 

 case the induction may be limited to a certain range of variation, 

 but the present law is as extensive as the organic world ; that is, 

 the ^^positioning" essential to it is found everywhere, from the 

 lowest to the highest, and in characters from the least to the 

 greatest in import. 



Let an application be made to the origin of tlie human species. 

 It is scarcely necessary to point out at the start the fact, univer- 

 sally admitted by anatomists, that man and monkeys belong to 

 the same order of Mammalia, and differ in those minor charac- 

 ters, generally used to define a '* family" in zoology. 



Now, these differences are as follows : In man we have the 

 large head with prominent forehead and short jaws ; short canine 

 teeth without interruption behind (above) ; short arms, and thumb 



* See " Odgin of Genera, and Method of Creation," Naturalists' Agency, Salem, 

 Massachusetts ; or McCalla & Stavely, 237 Dock Street, Philadelphia. 



f " On the Parallelism between Stages in the Individual and those in the Group 

 of the Tetrabranchiata." " Boston Society of Natural History," 4to, 1866, p. 203. 



:j: It is quite misunderstood by Darwin, as will be sufficiently evident from the 

 following quotation from the last edition of his " Origin of Species," 1872, p. 149: 

 " There is another possible mode of transition, namely, through the acceleration or 

 retardation of the period of reproduction. This has lately been insisted on by 

 Prof. Cope and others in the United States." This has only been dwelt on as 

 accounting for a very minor grade of differences seen in race and sex. 



