MOTOE OCULI COMMTJXIS. 133 



middle temporal fossa through the orbit and tearing the 

 nerve, can hardly be accomplished without touching the 

 ophthalmic branch of the fifth, which produces intense pain, 

 and is always followed by a more or less persistent contrac- 

 tion of the pupil. Several hours after the operation, how- 

 ever, the pupil is generally found dilated, and may slowly 

 contract when the eye is exposed to the light. In one ex- 

 periment, this occurred after the eye had been exposed for 

 an hour. But further experiments by Bernard show that 

 although the pupil contracts feebly and slowly under the 

 stimulus of light after division of the motor oculi, it will di- 

 late under the influence of belladonna, and can be made to 

 contract by operating upon other nerves. It is well known, 

 for example, that division or irritation of the fifth nerve 

 produces contraction of the pupil. This takes place after 

 division of the third nerve as well as before. Section of the 

 sympathetic in the cervical region also contracts the pupil, 

 and this occurs after paralysis of the motor oculi. 1 These 

 facts show that the third nerve is not the only one capable 

 of acting upon the iris, and that it is not the sole avenue for 

 the transmission of reflex influences. 



Bernard also found that galvanization of the motor oculi 

 itself did not produce contraction of the pupil, but this re- 

 sult followed when he galvanized the ciliary nerves coming 

 from the ophthalmic ganglion. 2 Chauveau states, that in 

 experiments upon horses, he has not observed contraction of 

 the pupil following galvanization of the motor oculi, though 

 he has sometimes seen it in rabbits. 3 At all events, contrac- 

 tion is by no means constant ; and when it occurs, it prob- 

 ably depends upon stimulation of the ciliary nerves them- 

 selves or irritation of the ophthalmic branch of the fifth, and 

 not upon stimulation of the trunks of the third pair. 



1 BERNARD, Systeme nerveux, Paris, 1858, tome ii., p. 201, et seq. 



8 Op at., p. 211. 



3 CHAUVEAU, Recherches pkysiologiques sur Torigine apparante et sur Forigine 

 reelle des nerfs moteurs craniens. Journal de la physiologic, Paris, 1862, tome 

 v, p. 274. 



