287 



which is simph' but comprehensively expressed Ijy the terms lieolth 

 and soundness. 



But let some change, though slight and ohscure, occur among the 

 elements of the case, some invisible agenc}^ of evil intrude among the 

 harmonizing processes going forward ; any disorder occur in the rela- 

 tions of cooperating parts; anj'thing appear to neutralize the effi- 

 ciencj^ of vitalizing forces ; any disability' of a limb to accept and to 

 throw back upon its mate the iDortion of the weight which belongs to 

 it to sustain, whether as the effect of traumatic accidents or other- 

 wise; in short, whatever tends to defeat the purpose of nature in 

 organizing the locomotive apparatus may be looked upon as a cause 

 of lameness. And it is not the least of the facts which it is imi^ortant 

 to remember that it is not sufficient to look for the manifestation of 

 an existing discordance in the action of the affected limb alone, but 

 that it is shared by the sound one, and must be searched for in that 

 as well as the halting member, if the hazard of an error is to be 

 avoided. The mode of action of the leg which is the seat of the 

 lameness will vary greatly from that which it exhibited when in a 

 healthy condition, and the sound leg will also offer important modifi. 

 cations in the same three i^articulars before alluded to, to wit, that of 

 resting on the ground, that of its elevation and forward motion, and 

 that of striking the ground again when the full action of stepping is 

 accomplished. Inability in the lame leg to sustain weight will imply 

 excessive exertion by the sound one, and lack of facility or disposi- 

 tion to rest the lame member on the ground will necessitate a longer 

 continuance of that action on the sound side. Changes in the act of 

 elevating the leg, or of carrying it forward, in both, Avill j)resent, 

 however, entirely opposite conditions between the two. The lame 

 member will be elevated rapidly, moved carefully forward, and 

 returned to the ground with caution and hesitancy, and the contact 

 with the earth will be effected as lightly as possible, while the sound 

 liml) will rest longer on the ground, move boldly and rapidl}^ forward, 

 and strike the ground promptly and forcibly. All this is due to the 

 fact that the sound member carries more than its normal, healthy 

 share of the weiglit of the body, a share wliich may be in excess from 

 1 to 250, and thus bring its burden to a figure varying from 251 to 

 500, all depending upon the degree of the existing lameness, whether 

 it is simply a slight tenderness or soreness, or whether the trouble 

 has reached a stage which compels the patient to the awkwardness of 

 traveling on three legs. 



That all this is not mere theory, but rests on a foundation of fact 

 may l)e established by observing the manifestations attending a single 

 alteration in the balancing of the ])ody. In health, the support and 

 equilibrium of that mass of the body which is borne by the fore 

 legs is equalized, and passes by regular alternations from the right to 

 the left side, and vice versa. But if the left leg, becoming disabled, 



