56 
THOMPSON YATES LABORATORIES REPORT 
The Eyes. 
I have been struck by the fact that, contrary to the statement by Magendie, no noticeable 
disturbance or ataxia resvilts in the motions of the eyeballs in consequence of section of the 
trigeminus, even after bilateral section. 
Remarks, 
The agreement between the results obtained for this nerve in the separate experiments has 
been close as compared with those obtained for some other nerves. The most striking exception 
has been in regard to the extension backward of the field in a young male Rhesus. In this 
individual the posterior boundary lay further back than in all the other experiments ; it included 
evidently a larger area than usual, into which the whole of the fossa of the helix of the pinna, and 
in the neck it reached the mid-ventral line on the thyroid cartilage instead of at a point altogether 
above that cartilage. 
It must be remembered that in the above experiments, which illustrate by the method of 
the remaining aesthesia the skin-field of the Vth nerve, the roots of the vagus as well as of the Vth 
were left untouched. After intracranial section of the vagus roots, in addition to the severe 
operation necessary for section of the cervical nerves, the condition of the animal precludes 
satisfactory examination of the cutaneous fields, so that exploration under those circumstances 
proves fruitless. There is, therefore, from the field above described as that of the Vth cranial, 
possibly to be deducted a small portion of the pinna in the immediate neighbourhood of the 
external auditory meatus. Whether the small field immediately surrounding the external meatus 
belongs to the vagus nerves, and anywhere extends beyond the actual limits of the field of the Vth 
cranial, is doubtful, but it may do so, and if it does the boundary given in my above experiments 
to the field of the Vth cranial extends on the middle of the outer face of the pinna somewhat too 
far backward, and is really there a combined boundary due to Vth and vagus together. The 
accompanying figure (fig. 2) shows the limits of the vagus field on the pinna, and also that of the 
field left when the Vth cranial as well as the vagus remains intact. The sketch is combined from 
experiments made on eight individuals, but in none of the individuals was the combined field first 
taken, and then the isolated field due to vagus only, because the shock accompanying such a 
procedure precludes satisfactory exploration of the surface. 
Of the whole Vth nerve, only the ramus tnandihularis includes in its sensory field the 
pinna, and it includes, as above mentioned, only a portion of the pinna. The boundary of the 
skin-field of the Vth at first sight seems, where it crosses the pinna, curiously irregular and 
arbitrarily placed. I find its course is, however, such as to include all those parts which are 
traceable to the tissue of the mandibular arch, and none of those traceable to the hyoidean. This 
can be well appreciated by tracing the boundary of the skin-field of the Vth on the figures of the 
development of the human pinna by W. His, jun.* On the pinna, therefore, the field of the 
Vth cranial nerve extends to, but does not trespass across the first visceral cleft, and the skin-field 
* W. His, jun. " Zur Entwickelungsgeschichte des Acustico facialis Gebietes beim Menschen." ' Archiv. f, Anat. u. 
Physiol.,' Anat. Abth., 1889. Supplement-Baml. 
