LOCOMOTOR ATAXY. 305 



felt ; the foot seems to rest on wool, soft sand, or on a bladder filled 

 with water. The horseman no longer feels the resistance of the stir- 

 rup, and has the strap shortened .... If the patient do not see his 

 movements, they will be still more uncertain ; if, while erect, he closes 

 his eyes, he immediately begins to sway about and totter. If his eyes 

 be closed while in the horizontal position, he cannot tell the location 

 of his limbs ; he cannot say whether the right foot be crossed over the 

 left, or the reverse." 



If, as some celebrated authorities assert, the posterior spinal col- 

 umns have the function of coordinating the movements, the anatomical 

 changes found on autopsy of tabes patients fully explain the symptoms 

 observed during life. We have said that the degeneration and atrophy 

 of the spinal cord constantly start from the posterior columns, and 

 that the posterior sensory roots almost always participate in the de- 

 generation. Leyden, who does not believe in a peculiar power gov- 

 erning the coordination of movement and its location in the posterior 

 spinal columns, has advanced a theory for the explanation of the disturb- 

 ances of coordination in tabes dorsualis, which, at first sight, is very enti- 

 cing. ' He explains the loss of power of coordination as due solely to 

 the diminished cutaneous and muscular sensibility. We must, indeed, 

 admit that Longet is correct in saying that a person, who has lost the 

 perception of his actions, who cannot judge of the position of his 

 limbs, who does not even know whether they are present, and, lastly, 

 who does not feel the floor under his feet, cannot walk erect, preserve 

 his equilibrium, and move his limbs with certainty and accordance. 

 Moreover, the peculiarities of the anomalies of movement observed in 

 tabes patients, the energetic lifting of the foot and its passive fall 

 when walking, the spasmodic, uncertain movements, their shooting 

 beyond the mark, all give the impression that the patient is so awk- 

 ward because he does not know what he has done till he has done too 

 much. Lastly, the fact that the helplessness of the patients is greatly 

 increased when they close the eyes, and cannot control their move- 

 ments by the sight, is favorable to the view that the anomalies of 

 movement in tabes dorsualis result from diminution of the cutaneous 

 and muscular sensibility. Nevertheless, Leyderfs theory is false. Its 

 correctness is opposed by the following facts : first, that in many pa- 

 tients the disturbances of sensibility are in marked disproportion to 

 the impairment of coordination of movement ; second, that in persona 

 whose cutaneous and muscular sensibility is far more diminished than 

 is the case in any tabes patients, there is often no indication of dis- 

 turbance of coordination. In Spaeth's work there is a full histcry of a 

 peasant, from Wurmlingen, who is known to all my students, as I 

 show him in my clinic almost every half year. This interesting pa- 



