EXAMINATION OF SOME SPINAL NERVES 
5 
Methods of Experimentation Employed in i he Preseni' Research 
Methods Employed. 
The method of experimentation employed in the present series of experiments has been 
similar to that made use of in Experimental Series No. II. of my previous communication, and 
has been already described in that on pp. 46-49.* It has been designated by HEADt as the 
' method of remaining assthesia,' a convenient title which I gladly adopt. A certain number of 
experiments on the brachial plexus were given in Experimental Series I. B, of my previous paper, 
and in them the nerve-roots were severed just outside the vertebral canal. In the experiments of 
the present paper the nerve-roots severed were in every case exposed, and cut through inside the 
vertebral canal ; in some instances the dura mater was not opened, and the whole spinal nerve — 
both its dorsal and ventral roots — was severed proximal to the spinal ganglion ; more frequently 
the dura was laid open, and then the particular dorsal (posterior) roots which it was desired to 
divide were severed without interference with the ventral (motor) roots. In the majority of the 
experiments the animal was allowed to recover from the operation, and time was given for the 
wound to heal completely before the animal was finally examined and killed. Strict asepsis 
and profound anaesthesia were maintained in every experiment throughout the entire operative 
procedure. 
With regard to the sections of the Vth cranial nerve a few words of description may be 
given. I have employed a method different from that elaborated by Magendie:|: and Bernard^ 
in the rabbit. ' Cette operation est difficile par la raison simple qu'oji ne voit pas ce qu'on fait.' 
I use the same method as I employed for intercranial section ot the oculomotorius,!| a method 
which offers the advantages that the nerve is seen at the time of section, can be divided 
deliberately either distal or proximal to the Gasserian ganglion, is exposed without removal or 
necessary injury to any part of the brain, or to any other cranial nerve, and leaves a wound which 
is comparatively trifling and soon healed. After a skin incision along the temporal ridge tlie 
temporalis is reflected in part, an ample trephine opening made in the temporal bone, and by 
lifting on wool pledgets the temporo-sphenoidal lobe, the floor of tlie middle fossa of the skull is 
brought to view. Through the dura mater lining this the Gasserian ganglion and its three nerve- 
trunks are easily seen — more easily in Mc4c. rhesus than in Mac. sinkus. The only difficult branch 
to sever is the ophthalmic, which it is not always easy to divide without doing damage to the 
other divisions. It is particularly easy to sever the whole nerve proximal to the ganglion. 
For examining the distribution of tlie motor roots of the spinal nerves, one mode of 
procedure adopted was similar to one previously used in my examination of the lumbo-sacral 
plexus.H 
The vertebral canal was opened, and a short series of tlie spinal nerves immediately above 
and immediately below the one to be investigated were divided ; a sufficient time, usually 28 days, 
sometimes longer, was allowed for degeneration to have play ; and finally, electrical excitation of 
* 'Phil. Trans.,' B., 1892, vol. 184. 
f 'Brain,' London, 1894, p. 469. 
\ 'Journ, (I. Ph)siol.,' vol, i, 302, 1824. 
§ ' Lecons s. 1. Systeme nerveiix,' vol. 2, pp. 48-57, 1858. 
II ' Proc. Roy. Soc.,' April, 1893. 
t\ 'Journ. Physiol.,' Cambridge, vol. 13, 658, 1892. 
