156 Keport of the State Geologist. 



intervention of a force, not well defined indeed, called Bathmism^ 

 which appears to be nothing else than a generalization of the 

 laws of acceleration and retardation, a subject which we shall 

 consider farther on. The interest of these works, abstracting 

 from them the purely metaphysical portion, is the application of 

 the theory, just explained, to Palaeontology. Admitting that 

 frequent exercise strengthens organs. Cope points out an easy 

 explanation of cases of interesting variations. The most striking 

 example is furnished by the origin of the structure of the foot in 

 the hoofed animals. Cope admits that the parts which compose 

 the members may become lengthened, under the influence either 

 of reiterated shocks or of tension. Hence originates the length 

 of fingers in the Digitigrades, the length of the tibia among the 

 Plantigrades, the development of the hind feet of the Jumpers, 

 such as the Kangaroos and Jerboas, and the fore feet of the 

 Sloths. 



The soldering of the bones and the development of the joints 

 receive a simple explanation, as does also the presence of 

 horns in the Kuminants. The evolution of these organs is fol- 

 lowed, step by step, in the fossil types dpwn to the present forms, 

 and is^^well developed in the sense indicated by the theory. It is 

 noticeable how emphatically the American school reverts 

 to the ideas for which Lamarck was so bitterly reproached, 

 and explains them in almost the same terms. But Cope goes 

 still farther, and considers animal will and intelligence to 

 be primordial causes of these variations ;* thus, at the outset, 

 it was because the aquatic animal sought to keep its legs 

 stiff, that those organs lost the power of flexibility in any 

 great degree; so too the Artiodactyls would intentionally 

 draw back the two extreme fingers behind the others in order to 

 protect them, and so on. It is unnecessary to insist on the 

 numerous and definite objections which are raised against these 

 exaggerations. The American school has, moreover, rendered 

 many other services to the transformist cause, and" we shall 

 presently see how the works of Hyatt put us in possession so far 

 as one extensive group is concerned, of the mechanism of the 

 production of new forms. 



* Cope, Origin of the Fittest. 



