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



Although it is impossible at present to determine the intracapillary 

 pressure in the ciliary processes, we may at any rate inquire whether there 

 is, in all experiments on the subject, the possibility of a difference of pressure 

 of 30 mm. Hg between intracapillary blood pressure and intraocular pressure. 

 In the case of a similar question in the kidney, we have been accustomed 

 to compare the aortic blood pressure with the ureter pressure, and have 

 regarded a difference of 40 mm. between these two pressures as satisfying 

 the necessary conditions for filtration through the glomeruli. A similar 

 comparison of arterial blood pressure and intraocular pressure leads to the 

 same result. Below we give the intraocular pressure and arterial pressure 

 as determined in a series of 20 experiments. It will be seen that in 

 every case there is a difference between the two pressures of at least 

 48 mm. Hg, the average difference of pressure in all the experiments being 

 84-8 mm. Hg. 



So far then our observations tend to support in every particular the view 

 laid down by Leber, namely, that intraocular fluid is produced in the ciliary 

 processes by a process of filtration, and that the sole factor determining the 

 amount of transuded fluid is the difference of pressure between the blood in 

 the capillaries and the fluid in the eye-ball. 



V. Influence of the Proteid Content of the Intraocular Fluid on the Intraocular 



Pressure. 



The fact that the intraocular fluid has to be filtered through the intercellular 

 channels of the endothelium bounding the spaces of Fontana and lining the 



