432 NERVOUS SYSTEM. 



undetermined. By immersing the eye in hot water, or in alco- 

 hol, this capsule may be readily detected on the posrerior face 

 of the cornea, and to the greater circumference of the iris; it 

 may even be traced for some distance on the front surface of 

 the latter. Some of the French anatomists, as Demours,* De- 

 scemet, and J. Cloquet, have asserted that it continued also 

 through the pupil to line the posterior chamber. An opinion 

 like this, from the extreme tenuity of the part, must be rather 

 the result of conjecture than of accurate observation: it has, 

 therefore, never found its way with full force into the writings 

 of anatomists. The condition of the pigmentum nigrum on the 

 posterior face of the ins, and on the ciliary processes, would 

 seem to be an objection to the existence of this capsule in the 

 posterior chamber of the eye. But, if it really does exist there, 

 as is pretended by M. Portal, who supposes it to be derived 

 from the tunica hyaluidea, its structure is incompara-bly more 

 delicate than that part on the cornea, and, indeed, is merely glu- 

 tinous. 



The Chambers of the Eye, till the seventh month of foetal ex- 

 istence, and sometimes later, are perfectly separated from each 

 other by the Membrana Pupillaris, called so from its position in 

 the pupil of the iris. It was discovered in 1740 by Wachen- 

 dorf, and is sometimes called after his name. It is a thin, deli- 

 cate, and transparent membrane, which is stretched across the 

 pupil from its circular margin, and may, by its colour, be readily 

 distinguished from the iris, when it has been made somewhat 

 turbid by alcohol. 



The Membrana Pupillaris consists, according to M. J. Clo- 

 quet,* of two laminae placed back to back, of which the fore- 

 most is a continuation of the membrane which lines the ante- 

 rior chamber of the eye, and the hindmost of that which lines 

 the posterior chamber. According to this, it may be noted 

 that each chamber has its distinct capsule. This membrane is 

 very vascular; some of its arteries are those which subsequently 

 form the internal arterial circle of the iris, and they radiate from 



Demours, Lettre, 1767. 



j- Journal Universelle dcs So. Med. Paris, 1818. Mem. sur la Memb. Pupill. 

 Paris, 1818. 



