BROWN- SEQUARD ON THE CENTRAL NERVOUS SYSTEM. 287 



arteries," as of great value, and as having done much to explain the 

 discrepancies upon this subject found between the experiments of 

 Schiff, "Wharton Jones, "Waller, and others. The constriction, says 

 Lister, of the arteries of the frog's webs, on irritation of the cord, may 

 be well demonstrated in the following simple maimer. The head of 

 the frog being depressed, so as to stretch the ligament between the 

 occiput and the first vertebra, a sharp knife is carried across the 

 spinal canal, immediately behind the head, so as to divide the cord 

 from the brain ; the toes may now be tied out and any observation 

 made upon the web, without the inconvenience generally produced 

 by voluntary struggles on the part of the animal, while at the same 

 time the use of chloroform is avoided, which is desirable, on account 

 of the irritating effect of its vapour on the web, and the constant 

 care required for its administration. If the webs be examined, im- 

 mediately after the operation, they will be found exsanguine from the 

 extreme constriction of the arteries, but in a few minutes this state 

 will gi\ r e place to dilatation, with free flow of blood. If now a fine 

 needle, curved at the end, be introduced through the wound in the 

 spinal canal, so that its point may penetrate a short distance into 

 the cord, while the eye of the observer is kept over the microscope, 

 the arteries will be seen to become constricted to absolute closure, 

 and to dilate again, after withdrawal of the needle. The experiment 

 may be repeated as often as may be desired, until the cord becomes 

 disorganised. Pfluger, in operating upon the large edible frog, suc- 

 ceeded in applying the galvanic stimulus to the anterior roots of the 

 sciatic nerve within the spinal canal, with the effect of producing 

 complete constriction of the arteries of the webs. Division of the 

 same roots, on the other hand, was followed by full dilatation of the 

 vessels. From this experiment it appears that the vaso-motor nerve 

 fibres pass along with the motor nerve roots. 



( To be concluded in our next.')* 



* It appears so desirable to complete the Bibliography of 1860 in the present 

 number, that we have determined, however unwillingly, to defer the publication of 

 the remainder of the Review of Dr. Brown-Sequard's labours, in older to allow 

 space for the excess of bibliographical matter. — [Eds.} 



VOL. I. — N. H. R. 2 P 



