I 6 s. HOLTH AND O. BERNER. M.-X. Kl. 



tions of others they are fairly complicated. Grynfeltt, for instance, states 

 that the dilatator ends at once at the base of the iris, as the contractile 

 fibrils cease while the nuclear part passes into the front lamina of the 

 epithelium on the ciliary processes. In this he is supported by Klinge, who 

 has recently made the dilatator muscle the subject of a comparative ana- 

 tomical axamination. Forsmark also states that the dilatator in this region 

 presents "relativ einfache \'erhältnisse", while Grunert, Faber, Merkel 

 and VON Szily describe a system of bundles of muscle, stating that in the 

 ciliar}' border the dilatator splits up into bundles, which are sent out all 

 round the dilatator in the form of off-shoots. \'on Szily and Juler describe 

 bundles which run forward to the pectinate ligament of the iris (where they are 

 even supposed to act as an escape for the vitreous humour; while Grunert 

 describes bundles forming "arcades". An outer sphincter is thus produced, and 

 Merkel and Jeropheeff have also described such a muscle, having found that 

 the dilatator-laver near the base of th:^ iris divides into bundles, which bend 

 back and intertwine, forming a thickened outer margin to the dilatator. Heer- 

 FORDT, however, has not seen any such thickened outer margin to the 

 dilatator; on the contrary he describes the periphery of the dilatator as 

 remarkablv thin, as the development of the contractile substance becomes 

 gradually weaker and weaker as the periphery is approached. Both Koganei 

 and Heerfordt, however, have described a change in the direction of the 

 (iilatator-elcnients from radial to circular with an approach to the periphery 

 of the iris. Forsmark, as already mentioned, has found the conditions 

 comparatively simple. He, too, has found that the dilatator-elements as a 

 rule changed their form, and took a circular direction on approaching the 

 peripherv of the iris. The simplest conditions have been found at the base 

 of the ciliary processes, as the fibril-stratum "in geringer Entfernung von 

 der Irisgrenze", begins to decrease and becomes steadily weaker until it 

 "genau an der Basis der Ciliarfortsätze gänzlich aufhört". 



In the ciliary depressions the conditions may be more complicated. 

 Here he has often found that the iris is folded and at the same time is 

 frequently thickened. This thickening is not generally due, however, to any 

 increase of the contractile substance, but to a change in the form of the 

 elements, which are flattened by lateral pressure, so that they may become three 

 times as high as they are broad; and in addition the folding of the iris 

 mav contribute to their deformation. Forsmark has also found in this region, 

 besides this diffuse and more apparent thickening of the dilatator, an actual 

 thickening produced by proliferation of the epithelial cells, which are moved 

 to the front of the stroma and are transformed into muscle-cells of the 

 mesodermal type. They are found in the strengthening bands which he has 

 found in varying numbers in all the irides he has examined. In describing 

 them he says that they begin a little within the inner end of the ciliary 

 processes, generally increase rapidly, and attain their greatest size when, 

 or soon after, they have descended into a ciliary depression, "und werden 



