490 ANIMAL PHYSIOLOGY. 
animals are of necessity very unsatisfactory in such a case, 
from the difficulty experienced in ascertaining their sensa- 
tions at any time, and especially when disordered. 
Pathological—_ A good deal of stress has been laid upon the 
teachings of locomotor ataxia in the human subject. The 
symptoms of this disease are found associated with lesions of 
the posterior columns of the cord. The essential feature is an 
inability to co-ordinate movements, though muscular power 
may be unimpaired. But such inco-ordination is not usually 
the only symptom; and, while the disease seems usually to 
begin in Burdach’s columns, the columns of Goll, the’ posterior 
nerve-roots, and even the cells of the posterior cornua, may 
be involved, so that the subject becomes very complicated. 
Co-ordination of muscular movements is normally dependent 
upon certain afferent sensory impulses, themselves very com- _ 
plex. It is to be remembered also that there are numberless 
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Fia. 347.—Diagram to illustrate probable course taken by fibers of nerve-roots on entering 
spinal cord (Schifer). 
connecting links between the two sides of the cord and be- 
tween its different columns of an anatomical kind, not to men- 
tion the possibly numerous physiological (functional) ones. 
We have stated above that section of one lateral half of the 
cord is followed by loss of sensation on the opposite side of the 
body ; but directly the contrary has been maintained by other 
observers ; while still others maintain that the effects are not 
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