1922. No. 4- MIOSIS CONGENITA SEL" MICROCORIA FAMILIARIS. 21 



the undeveloped cells in the front la^'er of the epithelium in my specimens 

 is Striking, as a comparison with Forsmark's description of them and the 

 drawing he gives (his fig. 6) with my figs. 7 and 8 is sufficient to show. 



With regard to the "mesodermal" type it will be necessary to refer 

 to Forsmark's work. His starting-point is the fact that many clever investi- 

 gators, such as WiDMARK and Grunert, have found nuclei in the membrane 

 of Bruch, whereas, according to the descriptions of numerous other writers, 

 this membrane has no nuclei. It is this much-debated question that Fors- 

 mark has made clear in his work. His investigations have shown him 

 that the ordinary muscle-epithelium cell is not the only form in which the 

 dilatator element occurs, but that "aufserdem in jeder Iris eine meistens 

 relativ kleine Zahl gewöhnlicher glatter Muskelzellen vorhanden ist." The 

 fact that muscle cells with axial nuclei are now and then found in the 

 membrane of Bruch need not, according to Forsmark, be explained by the 

 assumption of a folding and removal by constriction, for in his opinion the 

 strengthening fillets are in no way connected with the normal folds appear- 

 ing on the posterior surface of the iris. On the posterior surface of one 

 of these strengthening fillets, the epithelium, according to Forsmark, ex- 

 hibits no folding at all. He also states that the folding of the posterior 

 surface of the iris in man is very poorly developed. 



From their relatively rare occurrence in embryonal material and in 

 the irises of new-born children, compared with material from the eyes of 

 adults, Forsmark even considers it not improbable that the strengthening 

 bands are a post-foetal formation. 



The presence of muscle cells with axial nuclei in the fibril layer proves 

 to FoRSMARK "dafà die Dilatatorlage wenigstens zweischichtig werden kann." 

 In thus assuming that the strengthening bands may be formed by proli- 

 feration, he also shows that the newly-formed elements displaced in the 

 stroma change their appearance and take the form of the ordinary plain- 

 muscle cell. According to Forsm.a,rk it is upon the subepithelial position 

 that the ordinary form of the dilatator element depends, and this form is 

 conditioned in the contact with the posterior layer of the epithelium. When 

 this situation no longer exists, the cell assumes the form of the ordinary 

 mesodermal plain-muscle cell. This is also the case with the dilatator's nearest 

 relative, the sphincter, which is derived from the same organ, the secondary 

 optic cup, but from a more peripheral part of it than the dilatator. The 

 sphincter exhibits in a marked degree the ordinär}- mesodermal type with 

 its long, spindle-shaped cells with central, rod-shaped nuclei. 



Forsmark's view of the mesodermal type given above seems to me 

 to be strongly corroborated by my material, as it would be difficult to 



