DVORAK-THEOBALD: Schlemm's Canal of the iris with Descemet's membrane." In 1869 Iwanoff and Rolett9 discovered that in the human eye these iris continuations are much thinner and longer than they are in the ox or pig eye, and that the tissue actually corresponds to Fontana's canal in the human eye, and should be designated as Fontana's spaces. In 1908 Henderson'0 found that the structure forming the outer boundary of the angle of the anterior chamber is not a comb-like ligament for the iris root, but is a perforated or" cribriform" ligament of the ciliary muscle. He suggests that the term" cribriform ligament" isin every way a suitable one, being in absolute conformity with both the anatomic and the physiologic characteristics of the structure, while at the same time it is a term that facilitates the description and simplifies the conception of the filtration angle. Rochon-Duvigneaud (1892) described this tissue as a series oftrabeculae of characteristic structure-a sort of grill, having, perhaps for its purpose, the protection of the absorbing surface of the canal against deposits of cellular elements which can pass into the anterior chamber. This description and the name, trabeculae, have been accepted by later authors. The investigators of Schlemm's canal have been concerned with two main problems: First, to determine whether the canal should be assigned to the venous system or whether it should be regarded as a lymphatic lacuna; and, second, to establish the importance of the canal in the process of elimination of intra-ocular fluids, more especially of the aqueous humor.

In the extensive literature on the subject these two prob-lems and matters arising from them have been the main subjects of controversy. The theory that Schlemm's canal belongs to the blood system and is nothing more than a venous plexus has been sustained by Leber"(1873) and his school of thought. Troncoso12 (1905) and many others support the view of a purely lymphatic function of the canal. There is a third group, composed of Hamburger, 13 Weiss, 14