ATROPHY OF THE PLANTAR CUSHION. 
367 
not then agree with M. H. Bouley, who admits a maximum of in¬ 
tensity of action of the os coronge upon the ungual phalanx, when 
the metacarpo-phalangial joint is closed at its extreme degree, 
and that, on the contrary, it is when the two first phalanges are on 
the same line with the metacarpus, and receive integrally all the 
pressure, that the os coronae “ throws back on the navicular the 
greatest sum of the effort it supports.” 
One may become well satisfied with our opinion by making on 
a foot two antero-posterior sections, sufficiently distant from each 
other so that the lateral regions only are involved. By this experi¬ 
ment, one sees the navicular lowering progressively by degree as 
the phalangial axis is inclined, and raising to the level of the 
articular surface of the os pedis as this phalangial lever is 
straightened. Made upon the cadaver, this experiment would 
have only a specious value, if one infer from it the degree 
of lowering of the navicular bone. For that reason we will re¬ 
mark that we draw from it no other indication than that of deter¬ 
mining the conditions in which this bone receives a portion, more 
or less great, of the pressure of rest. 
Besides, our opinion is confirmed by the attitude of the animal 
when very lame. If the regions of the foot are very painful, as in 
suppurative corn, punctured wounds, involving the plantar apon¬ 
eurosis or even the plantar cushion only, what do we see ? The 
phalangial lever brought on the same line as the metacarpus. 
What on the contrary takes place in acute laminitis, when the os 
pedis, executing by its anterior border its displacement downwards 
and backwards, happens to compress the velvety tissue ? To 
come to standing position, the animal waits until the phalangial 
lever be lowered, so as to report as much as possible the 
pressure of rest on the navicular bone and the plantar cushion- 
To resume, in supporting at given steps of the standing, a 
great portion of the weight of the body, increased during 
locomotion by the force of impulsion, the navicular bone 
plays a very important part in the locomotion. And from 
this, with some exaggeration and by giving a different explana¬ 
tion of the fact, it has been said that at given times u it was 
on that small bone that all the sum of pressure was con- 
