THE MEMBERS. 191 



impulse transmitted to the trunk is no longer a trajectory approxi- 

 mating the horizontal, but becomes a short curve. 



The inclination of the osseous segments should therefore supply 

 this double purpose : it should aug- 

 ment the effectiveness of the articular 

 play without diminishing its extent. 



Each of the locomotory segments, 

 ^vhen viewed alone, presents for study 

 (Fig. 52) a limit of extension, A, and 

 a limit of flexion, B ; in a word, the 

 line or space of oscillation, AB, mark- 

 ing the limit of opening and of closing 

 the angle, be}'ond which it cannot ex- 

 tend, by reason of the resistance 

 offered by the articular surfaces and 

 the tension of the ligaments. piq 50 



Anatomy, through the researches 

 of Vincent and Goiffon^ upon the cadaver, has determined the extent 

 of this space, AB, in a very satisfactory manner ; but it becomes a 

 difficult problem when it is a question of the j)recise location of the 

 angle A OB in relation with the N-ertical line OX, or, A\^hat amounts to 

 the same thing, to fix the limited jjositions A and B, — points which 

 indicate the limit of the oscillation of 00 in the livinp- animal. 



It is in this direction that investigations should now be pursued. 

 It is possible, indeed, that if we could recognize the exact position of 

 these limits in horses of sjjeed, it would become easy to determine the 

 most desirable inclination of the bony levers. Evidently this inclina- 

 tion should assume the direction OC. bisecting the ano-le AOB. In 

 this case alone the space of oscillation will reach its greatest possible 

 limits ; for the extremity C, being equivalent from A and B, admits 

 of equal flexion and extension, the greatest of each that is possible. 

 All other inclinations diminish the one or the other of these movements. 



We have presented the only accessible observations that have been 

 made on this subject, excepting only the incomparably accurate re- 

 searches which MM. Marey and Pages ^ have undertaken with the aid 

 of instantaneous photographs of horses in locomotion. 



1 Vincent et Goiffon, M6moire artiflcielle des principes relatifs a la fidele representation des 

 animaux, t. ii., Paris, 1779. 



2 Pages, Analyse cinematique de la locomotion du clieval, in Comptes-Rendus de TAcade- 

 mie des sciences, 1885, p. 702 ; Marey et Pages, Analyse cinematique des allures du cheval, in 

 Comptes-Rendus, 1886 ; ibid., Mouvements du membre pelvien chez I'homme, I'eK-phant et le 

 cheval, iu Comptes-Rendus, 1887. 



