694 A MANUAL OF PHYSIOLOGY 



temporary. They are the results of shock ; they are not true ' defi- 

 ciency ' 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 normal state ; that, cut off as it is from the in- 

 fluence 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. Vaso-motor 

 tone comes back. The functions of defsecation 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. 



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

 this recovery of function. 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 that 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 

 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. Diges- 

 tion 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, inde- 

 pendently of the cerebro-spinal system, is itself possessed of regula- 

 tive powers. 



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 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 patho- 

 logical 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 



