86o THE CENTRAL NERVOUS SYSTEM 



In the first place, every operation of any magnitude on the brain or 

 cord is immediately followed by a depression of the functional power of 

 the nervous tissue distal to the lesion, a depression which may extend 

 far from the actual seat of injury and manifest itself by various phe- 

 nomena, which are groupe v d together under the name of 'shock,' better 

 termed spinal or cerebro -spinal shock, to distinguish it from the cardio- 

 vascular or surgical shock already mentioned (p. 190). Thus, when the 

 spinal cord of a dog is divided, e.g., in the dorsal region, all power, all 

 vitality, one might almost say, seems to be for ever gone from the 

 portion of the body below the level of the section. The legs hang limp 

 and useless. Pinching or tickling them calls forth no reflex movements. 

 The vaso-motor tone is destroyed, and the vessels gorged with blood. 

 The urine accumulates, overfills the paralyzed bladder, and continually 

 dribbles away from it. The sphincter of the anus has lost its tone, and 

 the faeces escape involuntarily. And if we were to continue our observa- 

 tions only for a short time, a few hours or days, we should be apt to 

 appraise at a very low value the functions of that part of the cord 

 which still remains in connection with the paralyzed extremities. But 

 these symptoms are essentially temporary. They are the immediate 

 results of the section; they are not permanent ' deficiency ' phenomena. 

 And if we wait for a time, we shall find that this torpor of the lower 

 dorsal and lumbar cord is far from giving a true picture of its poten- 

 tialities; that, cut off as it is from the influence of the brain, it is still 

 endowed with marvellous powers. If we wait long enough, we shall 

 see that, although voluntary motion never returns, reflex movements 

 of the hind-limbs, complex and co-ordinated to a high degree, are readily 

 induced. A few months after transection of the cord it is easy to show 

 that, although the dog cannot use the hind limbs for continuous pro- 

 gression, the machinery for executing the appropriate movements exists 

 in the cord. When, for example, the animal is held in the proper 

 position and given a slight push forwards, it may take two or three steps 

 before its legs give way. The regulation of the movements necessary 

 for the maintenance of equilibrium cannot be achieved when the control 

 of the higher centres is eliminated. In water, where the problem of 

 the maintenance of the normal position is solved by the mechanical 

 properties of the medium, the dog can use the hind-legs in swimming. 

 The tone of the resting muscles below the lesion is even somewhat 

 greater than normal. Vaso-motor tone also comes back. The 

 functions of defaecation and micturition are normally performed. 

 Erection of the penis and ejaculation of the semen take place in a dog. 

 A man with complete paralysis below the loins and destitute of all 

 sensation in the paralyzed region has been known to become a father 

 (Brachet). Pregnancy carried on to labour at full term has been 

 observed in a bitch whose cord was completely divided above the 

 lumbar enlargement. The severity and duration of spinal shock are 

 greater in the monkey than in the dog, in man than in the monkey, and 

 in the whole mammalian group than in the lower vertebrates. The 

 mechanism of its production has been much discussed, and will be 

 referred to on another page (p. 884). 



We cannot doubt that the spinal cord takes an important share in 

 the recovery of function after shock. But here again it would be 

 erroneous to conclude that everything is due to the cord. For Goltz 

 and Ewald have been able to keep dogs alive for long periods after 

 preliminary section of the cord in the cervical region and subsequent 

 removal of large portions of it. They find tha.t even after destruction 

 of the lumbar and sacral regions of the cord the external sphincter of 

 the anus, striped and even voluntary muscle though it be, regains its 



