1886.] 



On the Intraocular Muscles of Mammals. 



481 



x. (1.) Stimulation of the third nerve or the short ciliary nerves 

 gives rise to contraction of the ciliary muscle. 



(2.) Section of the third nerve gives rise to relaxation of the 

 ciliary mnscle. 



/3. When the ciliary muscle is not completely relaxed stimulation of 

 the long ciliary nerves gives rise to relaxation of the muscle, and in 

 consequence paresis or paralysis of accommodation. 



Stimulation of the track followed by the cervical sympathetic in 

 the neck gives rise to no alteration in the ciliary muscle, observed by 

 the images on the anterior surface of the lens seen through the 

 phakoscope, therefore the fibres to the ciliary muscle along the long 

 ciliary nerves must come from another source, and this I have little 

 doubt is the fifth, but here as with the pupil the difficulty is to 

 prevent the reflex along the third nerve. 



(3.) On section of the cervical sympathetic the arteries of the iris 

 are dilated. 



On irritation of the cervical sympathetic the arteries of the eye are 

 contracted. 



On section of the trigeminus there is also dilatation of the blood- 

 vessels of the iris and ciliary body according to Rogow. 



The separation of purely mydriatic fibres of the cervical sympa- 

 thetic from the vaso-constrictor has been already proved. 



The fact of tapping the anterior chamber of a normal or atro- 

 pinised eye being followed by myosis, is probably due to relaxation of 

 tension overfilling the arteries of the iris, as proved by an experiment 

 cited. 



In an animal bled to death the pupil contracts on faradaising the 

 third nerve or its branches : the pupil also dilates on stimulating the 

 cervical sympathetic. 



Ciliary Muscle. — In the bloodless eye accommodation has been seen 

 to take place by stimulating the third nerve. 



III. The drugs selected for the following experiments were cocaine, 

 atropine, and eserine, and the results are appended in the above order. 



Cocaine. A. On the Pupil. — 1. Cocainised pupil is of large size, 

 acting to light and accommodation. 



2. Cut third nerve, add cocaine and get increased mydriasis. 



3. Cocainised pupil not increased by section of third nerve, but no 

 longer acts to light and accommodation. 



4. Stimulation of third nerve induces myosis in the pupil under 

 cocaine. 



5. Stimulation of sphincter pupillee easily overcomes the cocaine 

 mydriasis. 



6. On the exsected eye cocaine induces mydriasis. 



7. On the eyes of animals bled to death, cocaine increases the 

 mydriasis due to haemorrhage. 



VOL. XL. 2 K 



