286 BEYIEWS. 



certain that the sympathetic nerve is, first, essentially, though not 

 exclusively, a motor nerve of blood-vessels ; secondly, that it originates 

 chiefly from the cerebro-spinal axis ; thirdly, that its paralysis is cha- 

 racterised by a dilatation of blood-vessels and afflux of blood, and 

 by the results of this afflux ; and fourthly, that its excitation, whe- 

 ther direct or reflex, is characterised by a contraction of the blood- 

 vessels, and the results of this contraction. The origin of the cervical 

 sympathetic has been indicated by Augustus "Waller and Budge, as 

 taking place between the sixth cervical and fourth dorsal vertebra?, and 

 it is probable that it has an origin even more extended. As regards 

 the other fibres of the sympathetic, Dr. Brown-Sequard believes, that 

 those going to the blood-vessels of the various parts of the head, 

 come out mainly from the spinal cord by the roots of the last cervical, 

 and first and second dorsal nerves. Their real place of origin he 

 thinks to be partly the spinal cord, and partly the higher portions of 

 the encephalon, but chiefly the medulla oblongata and the neighbour- 

 ing parts of the encephalon. In the other parts of the body, the 

 nerves of the blood-vessels seem to come chiefly from the cerebro- 

 spinal centre as well as the cervical sympathetic. 



On division of a lateral half of the spinal cord in the dorsal 

 region, we find in the lower limb on the same side, most of the effects 

 of a section of the sympathetic in the neck, viz. dilatation of the 

 blood-vessels, increase of heat and sensibility, and of the general vital 

 properties of the parts. Hence it seems to follow that the vaso- 

 motor nerve fibres follow, in the spinal cord, a course similar to, if not 

 identical with, the fibres for the propagation of commands of the 

 will to muscles ; so that, referring again to our diagram, a section of 

 the spinal cord in the dorsal region, suppose at 3, would be followed, 

 on the same side as the injury, by paralysis of motion and the symp- 

 toms of paralysis of the vaso-motor nerves, i. e. dilatation of the 

 blood-vessels, &c. In this fact, we find some means of accounting 

 for the hyperesthesia on the side of the lesion ; for the dilatation 

 of the blood-vessels is, as we know, accompanied by an increase in 

 the vital properties of the part, hence we find increase of heat and 

 increase of sensibility. "Whether this explanation is one altogether 

 satisfactory we shall consider afterwards. As the dilatation of the 

 blood-vessels, resulting from paralysis of the vaso-motor nerves, has 

 been experimentally shown in the head of the rabbit, after section of 

 the cervical sympathetic, and in the lower limb on the same side, 

 after section of a lateral half of the spinal cord, so the constriction 

 or spasm of these vessels has been made obvious as the result of gal- 

 vanic and other stimulation. The discovery of Dr. Brown-Sequard 

 as to the contraction of the vessels of the ear on galvanisation of 

 the cervical sympathetic after section, was a prime step in this direc- 

 tion. We regard likewise the researches of Mr. Joseph Lister* " On 

 the parts of the nervous system regulating the contractions of the 



* Philosophical Transactions, Part ii. 1858; also " On the early stages of Inflam- 

 mation," by the same author, in the same volume. 



