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



canal of Schlemm, in order to escape from the eyeball, suggests that the 

 resistance will be greater if the viscosity of the filtering fluid be increased in 

 consequence of raised proteid content. Indeed, one form of raised intra- 

 ocular pressure, the glaucoma accompanying inflammation of the ciliary 

 region, has been ascribed to the greater proteid content of the intraocular 

 fluid secreted by the inflamed vessels, and the consequent greater resistance 

 to the filtration of this fluid through the anterior angle of the eye. So far as 

 we are aware, there are no direct determinations of the relative rates of 

 filtration of normal salt solutions with and without proteid. We have, 

 therefore, in a series of animals, determined the intraocular pressure under 

 the two conditions : — 



(a) With normal intraocular fluid. 



(b) After replacing this fluid by blood serum. 



We have also compared the relative rates of filtration of normal salt 

 solution and of serum in the living and dead eye. 



In our experiments one eye of the animal was connected with a reservoir 

 and manometer containing Einger's saline fluid, while the other was connected 

 with a similar apparatus filled with filtered blood serum. 



In order to determine the intraocular pressure in an eye, in which the 

 normal aqueous humour had been replaced by serum, after introduction of 

 the hollow needle, the aqueous was allowed to escape through the side opening 

 in the cannula. Serum was then allowed to flow in for a time, and then the 

 contents of the anterior chamber again allowed to escape. The side tube was 

 then closed, an air bubble introduced into the capillary tube, and the pressure 

 determined at which the bubble moved neither backwards nor forwards. 



In nearly every experiment the intraocular pressure, during the first 5 or 

 10 minutes after the insertion of the cannula, was higher in the eye filled 

 with serum than in the eye filled with normal fluid. The difference, however, 

 rapidly diminished, so that 15 to 20 minutes after the beginning of the 

 observation the pressures were practically identical in the two eyes, and 

 remained so throughout the rest of the experiment. It must be remembered 

 that with the zero method used by us there is no movement of fluid into the 

 eye. Hence the fluid necessary to replace the loss by filtration and to 

 maintain the intraocular pressure is being constantly secreted by the ciliary 

 processes, and is probably of the normal composition, i.e., practically free 

 from proteid. We should therefore expect a gradual decline of the intra- 

 ocular pressure in the eye with serum, although hardly so rapid an 

 equalisation of the pressures on the two sides as we actually observed in 

 our experiments. 



