1082 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [lOi] 



we would look for a moviug body to ever swerve from traversing space 

 iu a right line if it were forever exempt from all disturbing resistances 

 and attractions along its path. Dr. Tomes, in his work on Dental Anat- 

 omy, second edition, finds it inconceivable that intrinsic forces are capable 

 of modifying the forms of the crowns of the teeth of Ungulates, appar- 

 ently unmindful of the fact cited by the writer that an inorganic crystal 

 line body as brittle as marble could be permanently bent if subjected to 

 a constant bending strain for many years. This, however, is only one 

 instance among many where biological writers have ignored the logic 

 of facts when dealing with the i)rinciples of the theory of evolution. 



In recently glancing over tlie Philosophic zooloijiquc the writer finds 

 that Lamarck had in that wo: k briefly recorded his views on digital 

 reduction, assigning increased use in running as a cause, as asserted 

 by Cope, Marsh, and the writer in later times. Some years since the 

 writer attempted to discuss digital reduction, when it " was suggested 

 that the fact of the number of toes being least wherever mechanical 

 fitrains were greatest and impacts most frequent and severe, might be 

 regarded as an efiect of such increased intensity of strains." Cope 

 afterwards showed that the grooving of the articular faces of the 

 limb-bones of certain Mammalia was probably due in i)art to such a cause. 

 The writer also called attention to the coexistence of accelerated digital 

 reduction in the pes with jumping or bounding habits, in consequence 

 of which the reduction began first in the hind limbs; pointing out, also, 

 in this connection, that man, the highest and only strictly bipedal pri- 

 mate, is the only one in which a perceptible digital reduction has be- 

 gun in the pes, so as to erdarge the inner toe. 



The specialization of the limbs of the modern Sloths has also been dis- 

 cussed by Lamarck, wno assigns their ])eculiar habits as the cause of 

 certain modifications of the limbs and other portions of the skeleton. 

 The writer, unaware at that time of Lamarck's published views, had 

 prepared an essay upon the same subject, in which he has given expres- 

 sion to certain views which were already expressed by the earlier au- 

 thor; but inasmuch as the writer had also discussed the digital and den- 

 tal reduction which occurs in this group, including the fossil species, it 

 has been decided to hand the manuscript to a pahcontological friend 

 competent to revise and bring it up to date for publication at an early 

 date. 



It has been thought proper to make these acknowledgments to one 

 of the most far-sighted intellects that has ever honored the pursuit of 

 biological investigation, for the reason that man3' of the students of to- 

 day seem forgetful of the man to whom indirectly they owe so much. 

 The writer also would acknowledge his indebtedness to this pioneer 

 evolutionist, and would frankly admit that Lamarck was the first to 

 ])erceive that morphological changes were traceable to the action of 

 forces, the effects of which we have been seeking to follow in this study 

 of the evolution or morphological ditterentiation of the fin-systems of the 

 Lyrifcra. 



