viii OCULAK MOVEMENTS 433 



to it is evidently the fact that after puncture of the cornea there 

 is no longer any pressure in the anterior chamber, so that the 

 rapid production of the fluid may be interpreted as the effect of 

 the disappearance of pressure. 



Leplat attempted to settle the question by experiment ; he 

 injected liquid paraffin into the anterior chamber of the eye in 

 rabbit, in order to hinder the outflow of aqueous humour, and 

 then connected the vitreous body with a manometer. He found 

 that immediately after injecting paraffin the manometer showed 

 a normal, intraocular pressure, but then rose suddenly ; in one 

 minute some 4 cmm. of fluid passed into the manometer. From 

 this it may be concluded that the content of the anterior chamber 

 of the eye is renewed in about 75 minutes in the rabbit, and in 

 about 50 minutes in man. 



The same questions arise in regard to the absorption of the 

 aqueous humour; in the first place by which structure is it 

 absorbed, and in the second how does absorption take place? 

 Without entering on the details, it may be stated that it is now 

 generally held that absorption takes place in the angle formed by 

 the iris and the cornea, through the trabeculum of the so-called 

 ligamentum pectinatum iridis. This conclusion was arrived at by 

 injecting different fluids into the anterior chamber. It was also 

 found that the rate at which absorption of the injected fluids 

 takes place under these conditions is proportional to the pressure 

 at which the injection is carried out (Hering, Leber, Adamiik, and 

 Jessner), whence it has been concluded that the normal process 

 by which absorption of the aqueous humour takes place is not 

 secretion, but filtration, due to excess of intraocular pressure over 

 that in the periocular lymph spaces. 



A similar conclusion has been arrived at by injecting coloured 

 fluids or suspensions of very fine powders into the anterior 

 chamber. It is, however, found that in addition to the angle of 

 the iris its anterior surface is also infiltrated with the injected 

 granules, and from this it is assumed that the iris also takes 

 part in the absorption of the aqueous humour. 



Certain experiments of Grandis and Moret (1901) on the 

 rabbit's eye, however, tend to show that the absorption of the 

 aqueous humour is not due to filtration. They connected the 

 anterior chamber with a manometer, and then observed the 

 variations of pressure for a considerable time, and found that it 

 first increased rapidly, and then more slowly, till after about 

 half an hour it became stationary, which according to these 

 authors cannot be accounted for on the view that the formation 

 of aqueous humour is an effect of simple filtration. In a further 

 series of experiments they found that if the pressure is arti- 

 ficially raised after it has become constant, a larger amount of fluid 

 is absorbed than has been added, so that after a certain time the 



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