432 



Mr. W. H. Jessop. On the Mydriasis [June 18, 



have in the compression and friction of the strata which has always 

 accompanied the upheaval of mountain- chains a vera causa for the 

 production of an amount of heat sufficient to produce one form of 

 metamorphic action — a form which can affect only particular regions 

 — I think it would be desirable, in order to show its distinctiveness 

 from either contact or normal metamorphism, to designate it by the 

 term of "Regional Metamorphism." In any case, I trust I have 

 shown cause for further inquiry. 



VIII. " On the Mydriasis produced by the local Application of 

 Cocaine to the Eye. 5 ' By Walter H. Jessop. Communi- 

 cated by Dr. Lauder Brunton, F.R.S. Received June 4, 

 1885. 



In a paper on " Cocaine," published in the " Practitioner " of January 

 1, 1885, and more fully in a paper on "The Cocainised Eye," before 

 the Ophthalmological Society on January 8th, 1885, I mentioned most 

 of the clinical facts concerning the drug and its action that had then 

 come under my own investigation and treatment. 



The object of this paper is to try and elucidate one of these facts, 

 namely : — The cause of the mydriasis accompanying the application of 

 cocaine to the eye. This research has been made chiefly on human 

 and rabbits' eyes by conjunctival instillation, and on rabbits' eyes by 

 experiments detailed below. The salt of cocaine used has been the 

 hydrochlorate obtained from Merck, of Darmstadt; the strength of 

 the solutions 2, 4, and 20 per cent., and these solutions have been used 

 fresh to avoid any changes by the growth of fungi, &c. By means of 

 a syringe the quantity of the solution used each time has been as 

 nearly as possible 1 minim. The pupil has been measured by a 

 Nettleship's pupillometer, or by means of a graduated thread, which 

 could be easily placed across the cornea. During each experiment the 

 subject was exposed as far as possible to the same light, so that the 

 differences in size of the pupils should be as exact as possible. 



The experiments on animals have been made strictly under the 

 influence of chloroform, and in animals allowed to live after such 

 experiments strict antiseptic precautions have been taken, so that 

 apparently they scarcely suffered except from the after effects of the 

 chloroform, the wounds being slight and quickly healed. 



If only one measurement of the pupils of rabbits is given it is the 

 transverse one. 



Experiment I. 



Starting first with the action of cocaine on the eye by conjunc- 

 tival instillation, I found as the result of over one hundred observa- 

 tions on the human eye the following facts : — 



