On the InnervaMon of Antagonistic Muscles. 



67 



knee seems to favour the reflex movement at those joints taking the 

 form of extension. The influence of the posture of the ankle- joint upon 

 the reflex movement at the hip seems negligible, for I have often 

 remarked the reaction at the hip to be unaltered, whether the ankle 

 were flexed or extended, at the time of excitation. 



In some dogs, when the spinal transection has been made at the 

 hinder end of the thoracic region, stimulation of the skin of the limb 

 evokes the usual primarj^ flexion at hip and knee wherever the locus of 

 the stimulus, except it be in the upper three-fourths of the front of the 

 thigh. Applied in this latter region the stimulus, if the limb be mid- 

 way between extension and flexion, not unfrequently evokes reflex 

 extension at hip and knee ; it does not evoke exbension if the initial 

 posture of the .limb be extension ; but if the limb be, at the time of 

 application of the stimulus, well flexed at hip and knee, reflex exten- 

 sion, instead of reflex flexion, becomes the rule. 



In the spinal frog, as in the spinal dog, flexion at hip and knee is 

 the regular reflex response of the musculature of the homonymous 

 hind limb to skin stimuli applied at any part of the surface of that 

 limlx This being true when the initial posture of the limb is, as when 

 pendent, one of extension at hip, knee, and ankle, a diff'erence becomes 

 evident when the initial posture is one of flexion at those joints. In the 

 latter case excitation of the skin within a small gluteal and pubic area, 

 lateral and somewhat ventral to the cloacal orifice, causes extremely 

 frequently not flexion at hip, but extension at that joint. Stimuli 

 (mechanical and chemical) to that area which evoke flexion at the hip- 

 joint when the initial posture of the limb involves extension at that 

 joint, evoke, when the initial posture is flexion, reflex extension at the 

 joint. 



These instances seem to indicate distinctly that the direction which 

 a spinal reflex movement elicited by stimuli similar in all respects, 

 including " locality," may take, is in part determined by the posture 

 alread}^ obtaining in the limb at the time of the application of the 

 stimulus. 



The reaction described above for the spinal frog holds good after 

 previous removal of all the skin from both hind limbs, with the 

 exception of the small gluteal piece necessary for application of the 

 skin stimulus. It would appear, therefore, that the influence of the 

 posture of the limb upon the spinal condition and reaction is not trace- 

 able to the nerves of the cutaneous sense-organs of the limbs. There 

 still remain the afferent nerves subserving muscular sense, and connected 

 with the sense-organs in muscles, tendons, and joints. These, as is 

 well known, are largely affected by the various postures of the limb, 

 even by such postures as are passively induced. 



