62 
THOMPSON YATES LABORATORIES REPORT 
arise, but the nerve-fibres rising from them are eventually in great part thrust quite beyond the 
confines of the original metamer. This trans-segmental trespass of the nerve-fibres is compara- 
tively slight in the skeletal musculature of the trunk, distinctly greater in that of the limbs, 
especially at the free apex of each limb, greater still in the sensory structures of the skin, and yet 
greater in the distribution of efferent fibres to the vertebral ganglia of the sympathetic, but 
greatest in the sensory fibres distributed from the root ganglion to the segments of the spinal cord. 
In a previous paper I have insisted on the want of segmental correspondence between the 
distribution of the sympathetic elFerents of the motor spinal root and the cutaneous distribution of 
the fibres from the cells of the corresponding spinal ganglion. To Langley we owe the 
suggestion (1891), and the demonstration (1893), that there is, on tlie other hand, close corres- 
pondence between the field of cutaneous distribution of the efferent fibres arising in a vertebral 
ganglion of the sympathetic and the cutaneous field of distribution of the fibres of the correspond- 
ing spinal ganglion. I appended to my previous paper mention of observations undertaken by 
myself in pursuance of his discovery of this relationship. I cannot too distinctly disclaim the 
slightest pretension to having myself previous to him put forward the view of the correspondence 
existing between the skin-field of the sympathetic ganglion and that of the spinal ganglion. I 
am induced to state this emphatically, because in an abstract of my paper by a foreign reviewer 
the doctrine is accredited to myself, and not to its real author. Dr. Langley, 
Vagus (?) Nerve. (Fig. 3.) 
After the Vth cranial and the highest three cervical nerves have been completely severed, 
the skin of the external auditory meatus, an 1 just round it, still remains sensitive. I think there 
is little doubt that this must be due to the still unsevered vagus nerve with the auricular branch 
from 'its ganglion of the root.' I have not, however, succeeded in obtaining an animal in suffi- 
ciently good condition after the operation of intra-cranial section of the vagus, in addition to 
intra-cranial section of trigeminus and section of the three highest cervical nerves, to ascertain 
with certainty the disappearance of the field after section of all those nerves. 
The field has been completely delimited in two experiments only ; the operation required 
for revealing it is somewhat severe. Lying, as the small field does, wedged in between the large 
fields of the Vth cranial and the Ilird cervical, and, as it were, imbedded in the anterior part of 
the field of the Hnd cervical, it is, in order to isolate it, necessary to sever the Vth cranial at its 
origin, and also the highest three cervical nerves inside the vertebral canal. When this has been 
successfully accomplished, a patch of aesthetic skin is easily demonstrable on the ear. It includes 
and immediately surrounds the external auditory meatus. Its shape and size, in the two experi- 
ments carried out upon it, were almost identical. It takes in practically the whole of the 
concha, the antitragus, part of the tragus and part of the antihelix ; also part of the fossa of the 
antihelix. Its limits can be better realized from fig. 3 than from verbal description. The surface 
inside the external auditory meatus was sensitive in my experiments as far inwards as could be 
tested with an ordinary probe. 
This tiny area, confined to the lateral region and widely distant from both the mid-dorsal 
