EVOLUTION OF FOSSIL CEPHALOPODA. 



233 



law has been rediscovered and renamed by Haeckel,* 

 "das biogenetische Grundgesetz " and by Wiirtenber- 

 ger.f But these naturaUsts, instead of adding anything 

 to Hyatt's definition, have failed to reach its clearness 

 and simplicity. The only real addition that has been 

 made is Cope's idea of retardation, | by which is ex- 

 plained the separation in the ontogeny of the descend- 

 ant of characters that occurred simultaneously in the 

 ancestor. Cope says : " The acceleration in the assump- 

 tion of a character, progressing more rapidly than the 

 same in another character, must soon produce, in a type 

 whose stages were once the exact parallel of a perma- 

 nent lower form, the condition of inexact parallelism. 

 As all the more comprehensive groups present this re- 

 lation to each other, we are compelled to believe that 

 acceleration has been the principle of their successive 

 evolution during the long ages of geologic time. Each 

 type has, however, its day of supremacy and perfection 

 of organism, and a retrogression in these respects has 

 succeeded. This has no doubt followed a law the re- 

 verse of acceleration, which has been called retardation. 

 By the increasing slowness of the growth of the indi- 

 viduals of a genus, and later and later assumption of the 

 characters of the latter, they would be successively 

 lost."* 



By a proper application of the law of acceleration as 

 defined by Hyatt and modified by Cope, all the facts of 

 biology may be explained ; there is no such thing as 

 "falsification of the record." But as yet the law has 

 had no great effect in classification, for most paleon- 



* Morphologic der Organismen, vol. ii ; and Anthropogenic, 

 1874. 



f Ausland, 1873, and Studien iiber die Stammesgeschichte der 

 Ammoniten, 1880. 



X Origin of the Fittest. * Origin of the Fittest, p. 142. 



