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Mr. E. E. Henderson and Prof. E. H. Starling. [Nov. 23, 



into the filtration angle of the eye, thus causing a mechanical obstruction, 

 which will be more marked the greater the intraocular pressure. Hence the 

 smaller amount of filtration in the atropinised or dead eye with dilated pupil, 

 as compared with that in the eye which has been put under the influence of 

 eserine. 



The figures of a typical experiment are given. 



Cat, anaesthetised with Ether. Blood pressure average 138 mm. Hg, with 

 only trifling variations throughout the experiment. 



Summary oj Conclusions. 



1. The intraocular pressure represents the pressure at which the rate of 

 formation of intraocular fluid is exactly balanced by its rate of escape 

 through the filtration angle of the eye. 



2. The production of intraocular fluid is strictly proportional to the 

 difference of pressure between the blood in the capillaries of the eyeball and 

 the intraocular fluid. 



3. No satisfactory method of measuring the intracapillary pressure in the 

 eyeball has been yet devised. The fallacies of Niesnamoffs method are 

 pointed out. Judging, however, from a comparison of the arterial pressures 

 and the intraocular pressures in a large number of animals under different 

 conditions, there is probably always a difference between the intracapillary 

 pressure and intraocular pressure, which is sufficient to account for the 

 production of the intraocular fluid, without assuming any active intervention 

 on the part of the cells of the capillary walls or of the ciliary processes. 



4. An increased proteid content of intraocular fluid slows its rate of 

 absorption in consequence of the mechanical hindrance of the proteid 

 to filtration. 



5. Filtration, i.e., the absorption of intraocular fluids, at high intraocular 

 pressures is favoured by constriction of the pupil and hindered by dilatation 

 of the pupil. The difference, however, is barely perceptible with normal or 

 low intraocular pressures. 



