FUNCTIONS OF THE SPINAL CORD 889 



tone, although it is temporarily lost after the first cervical section. 

 The bladder ultimately recovers the power of emptying itself spon- 

 taneously and at regular intervals. A pregnant bitch in which the 

 lumbar enlargement and the whole cord below it to the cauda equina 

 had been removed, and therefore all the nerve-roots supplying fibres 

 to the uterus cut, whelped in a normal manner, and the corresponding 

 mammary glands behaved exactly as the rest. Digestion went on as 

 usual when practically nothing of the cord except its cervical portion 

 was left. Certain vaso-motor phenomena were also observed which 

 suggest that the sympathetic system, independently of the cerebro- 

 spinal system, is itself possessed of regulative powers (p. 183). 



Secondly, we must not run into the opposite error, and assume, 

 without proof, that all the functions which the brain or cord is capable 

 of manifesting under abnormal circumstances are actually exercised by 

 either when, under ordinary conditions, it is working along with and 

 guiding, or being guided by, the other. For example, in many animals 

 certain of the reflex powers of the cord are, if not increased, at all events 

 more freely exercised when the controlling influence of the higher centres 

 has been cut off than when the central nervous system is intact. 



Thirdly, there is another class of phenomena which we must make 

 allowance for, and perhaps more frequently in the case of pathological 

 lesions in man than in experimental lesions in the lower animals. This 

 is the class of ' irritative ' phenomena. The irritation set up by a blood- 

 clot or a collection of pus, or in any other way, in a wound of the grey 

 or white matter, may cause a stimulation of nervous tracts by which, 

 for a time, the ' deficiency ' effects of the lesion may be masked. 



In the fourth place, we must not hastily conclude that, when no 

 obvious deficiency seems to follow the removal of a portion of the central 

 nervous system, the function of that portion must necessarily be of 

 such a nature as to give rise to no objective signs. For there is reason 

 to believe that, to a certain extent, the function of one part may, in its 

 absence, be vicariously performed by another. 



Bearing in mind the cautions we have just been emphasizing, we 

 may broadly distinguish between the functions of the cord (including 

 the bulb) and those of the brain proper by saying that the cord is 

 essentially the seat of reflex actions, the brain the seat of automatic 

 actions and conscious processes. But neither of these conceptions 

 is entirely correct. Both err by defect and by excess. The brain, 

 it is true, is pre-eminently automatic. The movements which are 

 started in the grey matter of the cerebral cortex are pre-eminently 

 voluntary (p. 946), but we cannot deny to the brain the possession of 

 reflex powers as well. The movements in which the only nerve 

 centres concerned are those of the spinal cord are above all reflex 

 (p. 897)- But some of its centres, and especially those lying in the 

 medulla oblongata e.g., the respiratory centre are, much as they 

 are influenced by afferent impulses, capable of discharging auto- 

 matic impulses too. And while consciousness is certainly bound up 

 with integrity of the brain, and in all the higher mammals is asso- 

 ciated with cerebral activity alone, it has been plausibly maintained 

 that the spinal cord, even of such an animal as the frog, may also be 

 endowed with something which might be called a kind of hushed 

 consciousness. Whether this be so or not for the frog, with its 



