270 



Dr. C. E. Beevor and Prof. V. Horsley. [June 7, 



In every case the animal was narcotised with ether. 



(1.) For the exposure of the nerves at the base of the cranial 

 cavity it was found possible to rapidly remove a cerebral hemisphere, 

 clamping the carotid and other arteries, then to divide the tentorium 

 and to remove the major part of the cerebellar hemisphere of the 

 same side, so as to admit of prolonged and numerous observations 

 before the animal died. In all we have made eight experiments, and 

 in every case we have operated on the same kind of monkey, i.e., 

 Macacus sinicus. 



(2.) For the exposure of the nerves outside the skull we found it 

 easy to lay bare the upper cervical nerves and those of the cranial 

 division in the anterior triangle by turning forward a triangular 

 flap of skin, ligaturing and removing the external jugular vein, and 

 dividing and turning aside completely the sternomastoid muscle. 

 Finally, the parotid gland and digastric muscle (posterior belly) were 

 drawn up with hooks, the head being turned to the opposite side. 



The chorda tympani was readily exposed without injury, in the 

 tympanic cavity, before the dissection of the triangle by cutting away 

 the posterior wall of the external auditory meatus and the posterior 

 half of the tympanic ring. The facial nerve was subsequently exposed 

 in the stylomastoid foramen and aqueduct. 



The nerves were in each case raised up from their position and 

 stimulated in the air by the faradic current through fine platinum 

 electrodes, the area of the operation having been gently dried. 



The current employed was from the secondary coil of an ordinary 

 du Bois-Reymond inductorium, supplied by a 1 litre bichromate cell. 

 The experiment was carefully begun with the secondary coil at a 

 distance of 30 cm. from the primary, this interval being very rarely 

 diminished to more than 15 cm. (zero being of course the point where 

 the secondary coil completely overlaps the primary). 



Further Observations respecting the Examination of each Nerve. 

 A. Cranial Division. 



Vth Nerve. — Excitation of the motor root of the trigeminus evoked 

 powerful closure of the jaws, and although the muscles of one side 

 only were in action, the teeth were approximated without any lateral 

 deviation of the lower jaw. 



Vllth Nerve. — The motor distribution of the facial nerve has for 

 the most part been well known for some time. However, we consider 

 that, unfortunately, a very fundamental error respecting this distri- 

 bution has crept into the text-books, it being supported by one 

 anatomical authority following another, and, moreover, having been 

 accepted by clinicians as an important aid in the differential diagnosis 

 of facial paralysis. We refer to the supposed supply of motor fibres 



