1886.] On the Intraocular Muscles of Mammals. 



483 



17. Tapping the anterior chamber of an eye under atropine pro- 

 duces contraction of the pupil. 



18. On exsected eye atropine produces mydriasis. 



19. On the eye of an animal bled to death, atropine dilates the 

 pupil. 



20. Atropine also dilates the pupil after death. 



B. On the Ciliary Muscle. — On the ciliary muscle atropine pro- 

 duces relaxation, and if used for a long time complete paralysis. 



From the above experiments on atropine, and the fact that else- 

 where atropine paralyses the unstriped muscular tissue of the body, it 

 may be assumed that it acts so on the intra-ocular muscles. 



The effect of section of the cervical sympathetic and trigeminus, 

 preventing extreme atropine mydriasis, may be explained by their 

 effect on the blood-vessels producing turgescence of the iris, and 

 therefore acting against the elastic recoil of the sphincter. 



E serine. A. On the Pupil. — 1. Eserine on the pupil induces myosis. 



2. It contracts the pupil of an animal after section of the 

 third nerve or short ciliary nerves. 



3. In full eserine myosis faradaic excitation of the third nerve does 

 not increase the contraction of the pupil. 



4. Section of the fifth nerve in front of the Grasserian ganglion, and 

 on putting eserine into the eye the pupil contracts as usual. 



5. Faradaic stimulation of the cervical sympathetic overcomes 

 eserine myosis if partial, but if complete it has no effect. 



6. Cut cervical sympathetic in the neck and eserine still induces 

 myosis, even after the section has been made three months. 



7. For an animal bled to death I have seen eserine induce myosis. 

 B. On the Ciliaiy Muscle. — Eserine produces contraction of the 



ciliary muscle, giving rise to spasm of accommodation. 



In cases of palsy of the third nerve eserine induces contraction of 

 the ciliary muscle. 



The action of eserine on the intra-ocular muscles can be explained 

 by its stimulating directly the muscular tissue. 



The antagonism of atropine, eserine, and cocaine is next discussed, 

 and found to agree with the action attributed to each alkaloid. 



Conclusion.— From consideration of the foregoing experiments and 

 observations the writer describes the intra-ocular muscular system as 

 consisting of two circular muscles, the pupillary and ciliary. These 

 are supplied, the first by three nerves, the third, the cervical sympa- 

 thetic, and the fifth, and the second by the third nerve and the fifth. 



The muscles are capable of extreme relaxation and contraction, 

 owing to the elastic supports they have. 



Section of a nerve producing contraction does not give rise to com- 

 plete contraction of the muscle, nor does section of a nerve producing 

 relaxation have as a sequel complete relaxation. 



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