THE SENSES. 269 



up the anterior and posterior chambers of the eye, and is probably 

 secreted by the Iris and the corpus ciliare (according to others by 

 the vitreous body, &c.). 



a. Camera oculi anterior is the space between cornea and Iris, measures in 

 the longest diameter from before backwards about one line, is at its circum- 

 ference encompassed by the anterior extremity of the lig. ciliare, and stands, 

 through the pupillary aperture, in connexion with : 



b. Camera oculi posterior, that is, the small (one-third of a line) space be- 

 tween the posterior wall of the Iris and the anterior surface of the capsule of 

 the lens. The two chambers contain about five grains of fluid. The ante- 

 rior chamber is, in the fetus, shut out from the posterior by the pupillary 

 membrane. An aqueous membrane which lines the two chambers as a closed 

 sac, for which the membr. Descemetii is said to pass, is not to be found. 



503. 2. Lens crystalling the crystalline lens, 



a round, biconvex, colourless, transparent body, is situated, narrowly enclosed 

 by its capsule, behind the pupilla, at the boundary of the anterior fourth of the 

 globe, and its axis in the axis of the pupil. 



Its anterior surface is flatter, one line and a half distant from the cornea ; 

 the posterior more convex, four lines distant from the fundus of the eye. Its 

 margin is encompassed by the folds of the zonula Zinnii, and encircled by 

 canalis Petiti. 



Structure. The substance of the lens contained in the capsule becomes 

 thicker from without inwards. The anterior portion, almost a thin fluid, the 

 so-called liquor Morgagni, contains cells, like the gelatinous portion found 

 behind it, with a very delicate membrane, which, when their water evapo- 

 rates, become dark and granular. Upon the cellular layer narrow, straight 

 fibres follow, which form layers, and lie close upon one another, like the 

 scales of an onion, inwards towards the middle thickened into a nucleus (of 

 a gummy consistency). Each lamina consists on the anterior surface of the 

 lens of three, on the posterior of four triangles, between which a space in the 

 form of a A or )=( remains, to which the fibres converge inwards, so that the 

 lens breaks up into three to four (or more) wedge-shaped pieces by the action 

 of an acid, boiling water, or even merely by heat. 



The substance of the lens contains, more than the half, water, and much 

 albumen, (Globulin according to Berzelius; Casein, Fr. Simon.); it becomes 

 cloudy after death (whether by coagulation ?), and coagulates in sulphuric and 

 phosphoric acids, which last does not make it opaque. 



The capsule of the lens, capsula lentis, a simple membrane, clear as water 

 (under the microscope a faint yellow), in adults non-vascular, is smooth, 

 strong, stiff, and distinctly thicker on the anterior wall than on the posterior. 

 Its anterior wall looks freely into the posterior chamber of the eye, lies quite 

 open when the pupil is widely dilated, and is firmly connected at the margin 

 with zonula Zinnii; its posterior wall lies in the fossa-hyaloidea of the vitre- 

 ous body. 



