SPINAL CORD AS A PATH OF CONDUCTION. 173 



confidence, however, cannot be placed in this conclusion, since the 

 lesions in question were not strictly confined to the fasciculus 

 in question, although clinical evidence indicates that the fibers 

 conveying impulses of pain or of pain and temperature lie in the 

 ground bundles in the neighborhood of this tract. The only posi- 

 tive indication that we have concerning the physiological value of 

 this specific tract of fibers is given by their histology in the fact that 

 they end, for the most part, in the cerebellum. The cerebellum, 

 we know, may be removed in dogs and monkeys without loss of the 

 sensation of pain, temperature, or touch, and this fact speaks 

 strongly against the view that either the cerebellospinal or the 

 superficial anterolateral fasciculus is concerned in the conduction of 

 these cutaneous sensations. From a physiological standpoint we 

 should be inclined to believe that both of these tracts conduct non- 

 sensory afferent impulses from the tissues lying under the skin, 

 particularly from the muscles, tendons, and joints. It would seem, 

 therefore, that all the long ascending tracts in the posterior and 

 lateral funiculi of the cord may be made up of fibers of muscular 

 sensibility, using this term in a wise sense to include the deep 

 sensibility of the joints, tendons, and muscles. The immense 

 importance of muscular control in the maintenance of life and in 

 defense against enemies may explain, upon the doctrine of the 

 struggle for existence, why the long paths should have been devel- 

 oped first in connection with this sense. 



The Spinal Paths for the Cutaneous Senses (Touch, Pain, 

 and Temperature). — From the facts stated in the last two para- 

 graphs it would seem probable that the spinal paths for touch, 

 pain, and temperature must be along the short association 

 tracts of the proper fasciculi of the lateral and anterior funiculi. 

 There is evidence from the clinical side that the paths of con- 

 duction for these senses are separate. In the pathological 

 condition known as syringomyelia, cavities are formed in the 

 cord afi'ecting chiefly the central gray matter and the contiguous 

 portions of the white. In these cases a frequent symptom is 

 what is known as the dissociation of sensations; the patient 

 loses, in certain regions, the sensations of pain and temperature 

 (analgesia and thermo-anesthesia), but preserves that of pressure 

 (touch). Facts of this kind indicate that the paths of conduc- 

 tion for touch are separate from those for pain and temperature, 

 but little that is positive is known regarding the exact location of 

 these paths. The fibers of pain and temperature probably end 

 in the gra}' matter of the cord (posterior column) soon after their 

 entrance, and the path is continued upward by tract cells whose 

 axons cross to the other side and enter the fasciculi in the antero- 

 lateral funiculi,* but the number of such neurons concerned in 



* For discussion, see Bertholet, "Le Nevraxe," 1906, vii, 283, for the 

 lower animals; Head and Thompson, "Brain," 1906, p. 537, and Thompson, 

 ■"Lancet," 1909, for man. 



