FUNCTIONS OF THE SPINAL CORD. 641 



to a group of cells communicating with those in the anterior horn of its own 

 side. If the impression be strong, it is transmitted to the opposite side through 

 the connecting fibres that pass from the cells of one anterior horn, or possibly 

 of one posterior horn to those of the other. The motor cells of the Cord are 

 brought into communication with the Brain through the intermediation of the 

 cells in the Corpora Striata. A peculiar condition described by Schiff 1 as 

 Analgesia may here be alluded to. It consists in the retention of the capability 

 of perceiving sensations of touch, though the most severe injuries to nerves 

 produce no "sensations of pain ( 504). This condition may be induced, 

 according to Schiff, by division of the whole Spinal Corel with the excep- 

 tion of the posterior columns, also by rapid abstraction of blood ; and it 

 may be observed in the early stages of the administration of ether or chloro- 

 form. It seems to be questionable, however, whether this is not rather to 

 be considered as a state of blunted common sensibility. There can be little 

 doubt respecting the origin of vaso-motor fibres from the Spinal Cord, by 

 which the calibre of the vessels and the temperature of the parts supplied 

 by them is regulated. Finally, physiological experiments have shown that 

 in animals at least (rabbits), and the experiments are supported by the re- 

 sult of pathological investigations in man, there is a genito-urinary centre 

 presiding over the sexual movements, and those of micturition, which occu- 

 pies the lower part of the cord ( 276). As a sequel to the preceding con- 

 sideration of the Spinal Cord as a conductor of motor and sensory impres- 

 sions, and as an independent centre, the following summary by M. Brown- 

 Sequard 2 of the results in Man of any injury damaging the whole transverse 

 thickness of a small portion of one lateral half of the cord is instructive. 

 There may be observed under these circumstances: A. On the same side 

 1. Paralysis of voluntary motion ; 2. Hypertesthesia for sense of contact, 

 for tickling, for pain, and for temperature in the paralyzed parts; 3. An 

 anaesthetic zone of small extent, corresponding to the parts supplied by 

 nerves which take their origin from that part of the Spinal Cord situated 

 immediately below the lesion ; 4. Hypersesthesia in a greater or less extent 

 of surface above the zone of diminished sensibility; 5. Absolute or relative 

 elevation of temperature in the paralyzed parts, and often also in those 

 parts of which the sensibility is exalted, but not in the parts which are not 

 paralyzed ; 6. Phenomena indicating paralysis of the origins of the great 

 sympathetic nerve in the neck, when the lesion has occurred in the cervico- 

 brachial enlargement. B. On the opposite side 1. Complete anaesthesia 

 as regards contact, tickling, pain, and temperature in the parts which cor- 

 respond to those that are paralyzed on the opposite side ; 2. Perfect pres- 

 ervation of the voluntary movements and of the muscular sense ;. 3. A zone 

 of exalted sensibility of small extent and feeble in degree, situated in the 

 parts above those the sensibility of which is diminished. From his numer- 

 ous observations, he believes he is justified in drawing the conclusion already 

 stated ( 500, 501), that complete decussation of the conductors of the 

 various kinds of sensibility occurs in the cord, with the exception of those 

 only conveying the muscular sense. 



506. The endowments of the Medulla OUongata do not seem to differ from 

 those of the Spinal Cord in any other respect, than in the special nature of 

 the reflex movements to which it ministers. This part of the Cranio-Spinal 

 Axis has been regarded by some Physiologists, indeed, as the peculiar seat 

 of vitality ; since, although the other Encephalic masses may be withdrawn 



1 Physiologic, 1859, p. 252. 



2 Journal cle la Physiologic, vol. vi, Oct. 18G3, published in December, 1865, pp. 

 124, 232, and 581 ; and Archives de Physiologic, 1868, p. 610. 



