112 A STUDY OF SOME 



cending curve depending upon the centre of rotation being trans- 

 ferred to the tip of the great toe. This curve passes insensibly 

 into another, caused by the flexion of the leg upon the thigh and 

 by the onward movement of the liip. It is to be noticed that 

 ■ flexion of the leg is much more marked than in the normal con- 

 dition ; consequently, the corresponding portion of the curve is 

 higher. The fall of the foot to the ground we noticed, both 

 in line 6 and in Fig. 6, is somewhat irregular ; also, that the 

 heel fails to make the slight ascent which occurs in the normal 

 walk just before the impact on the ground; and, finally, that 

 when the impact does take place it is made by a sudden descent 

 or fall. 



The writer does not by any means desire to impress the reader 

 as though these curves {i.e., of Fig. 8) indicate the invariable 

 paths through which every ataxic must move his feet. He does, 

 however, insist that the two principal factors indicated, namely, 

 the increased lateral sway and the increased height to which 

 the foot is raised, are constant. To these must be added irregu- 

 larity of movement, as irregularity is itself an essential feature 

 of ataxia. An interesting confirmation of the constancy of 

 these factors is seen in Plate 550. Here, a Dane, aged fifty-two 

 years, with a history of a long-standing and increasing ataxia, 

 was first photographed (see upper series) while walking with the 

 eyes open. An examination of the figures shows that although 

 the gait differs from the normal in the two principal factors de- 

 scribed, yet, owing to the guidance afforded by his eyes and to the 

 evident effort he is making, as shown in the throwing back of the 

 shoulders and the fixation of the trunk, his walk is tolerably good. 

 In the lower series, however, he was photographed ivhile his eyes 

 were closed. A remarkable change is at once observed, and it 

 needs no elaborate study of the trajectories to show what the chief 

 elements of the change are. It is seen at once that the foot is 

 raised much higher from the ground, and that the lateral sway is 

 enormously increased ; also, that the successive steps are more 

 irregular. In this series, also, the abrupt descent of the foot upon 

 the ground is again noticed, the entire sole impinging or flopping, 

 as it were, upon the ground at once. In Plates 546 and 554, which 

 represent cases of ataxia more or less advanced, the essential points 

 of the ataxic gait are pronounced, as they are also in Plate 549. 



