v SPINAL COED AND NERVES 353 



(V) The accelerator spinal centres for the heart are in approxi- 

 mately the same region as the cilio-spinal centre (Vol. I. p. 336). 



From this enumeration it is plain that not only the nerve- 

 centres for the organs of animal life, but to some extent those of 

 the visceral function also lie in the spinal cord. 



Since the innervation of the organs of visceral life is supplied 

 directly by the sympathetic ganglion system, a final and interesting 

 problem here presents itself. Are the functions of the sympathetic 

 system subordinate to those of the spinal centres, or can they 

 subsist independently of them ? 



To solve this question it is necessary to study the immediate 

 and remote eti'ects of ablation of the cord. Previous to the 

 remarkable results obtained by Goltz and Ewald in 1896, such a 

 research would have been impossible. They first demonstrated 

 that dogs can survive for many months in a good state of health 

 after repeated removal of parts of the cord from below up to the 

 cervical region ; so that the opinion previously maintained by 

 every one that in warm-blooded vertebrates the cord is absolutely 

 indispensable to life, as the regulator of the nutritional processes, 

 the vascular tone, and the thermal equilibrium of the organism- 

 is fallacious. 



As we have already seen (p. 330), after simple section of the 

 dorsal roots of the spinal nerves the tissues that become insensitive 

 are more liable to injury than before. This is, of course, most 

 marked in the posterior part of the dog with amputated cord. 

 Patches of decubitus, pustules, erythema, oedema, especially near 

 the genital organs and anus, are extremely likely to appear ; but 

 these cutaneous lesions can be avoided or cured by constant and 

 scrupulous cleanliness. By degrees, however, the skin of the cord- 

 less animal gradually acquires an increasing resistance to external 

 injurious influences. 



Even more important to the survival of these animals is the 

 avoidance of a fall in the blood temperature, which is liable to 

 occur directly after simple transection of the cord, by enclosing 

 the animal in a chamber with double metal walls, between which 

 warm water is continually circulated. 



The persisting activities in the posterior part of the animal 

 that has lost its thoracic and lumbo-sacral cord are far more 

 numerous than would be anticipated a priori from what we have 

 learned experimentally with regard to the functions of the spinal 

 cord. The immediate effects of removal of the cord are principally 

 due to operative shock. After a few months they diminish 

 sufficiently to give a clear idea of the great physiological im- 

 portance of the sympathetic ganglion system, in so far as it is 

 capable of acting on the organs and tissues of vegetative life, 

 independently of the spinal system. 



Directly after ablation of the thoracic and lumbo-sacral cord, 



VOL. Ill 2 A 



