1923. No. 23. A CASE OF CONGENITAL MIOSIS. 9 



a decided impression of there having been a strong pull upon the periphery 

 of the iris, causing it to stretch considerably. 



The condition of the dilatator muscle behind the sphincter presents no 

 features of special interest; it was as I have described it in my previous 

 paper. In the intermediate zone also, the dilatator as a rule appears very 

 distinctly, so distinctly that it is not at all necessarv to depigment the 

 sections in order to see it. In fig. 6 I have reproduced a microphotograph 

 of it from this region, and here the membrane of Bruch is distincth- seen. 

 For purposes of comparison I would ask the reader to look at fig. 7, which 

 is taken from a place in which the dilatator is absent. Both photographs 

 are taken with about the same magnification and from sections that have 

 not been depigmented. 



It must not be supposed, however, from the description that I have so 

 far given of the dilatator muscle in Axel B.'s eyes, and especiallv from 

 my reference to fig. 6, that the dilatator is o/ways present in the inter- 

 mediate zone. In the depigmented series, where the conditions can, of course, 

 be most easily judged, small spots may generally be found in this region 

 where the dilatator is altogether absent, and where there is thus complete 

 agreement between the eyes of the brother and sister. The photograph 

 reproduced in fig. 8 shows one of these spots, in which there is not the 

 slightest trace of an}- contractile substance in front of the iridian epithelium, 

 and where the front stratum of this epithelium consists of long fusiform 

 cells with a rather long, rod-like nucleus. As the photograph distinctly 

 shows, these long fusiform epithelial cells go right up to the stroma, which 

 also exhibits a peculiarly loose structure, ver}- much resembling mucous 

 tissue. In fig. 9 I have reproduced a photograph taken from the same sec- 

 tion as fig. 8, with only a very slight displacement of the preparation; and 

 it will be seen that a slight development of the dilatator has taken place 

 here, as in front of the epithelium, between it and the stroma, there are 

 some contractile fibrils, which have given a dark tone of colour to the layer. 



These patches where there was no dilatator muscle were, as I have 

 said, never large. In my various series of transverse sections, therefore, I 

 always found a continuous dark line produced by the severed contractile 

 fibrils in front of the iridian epithelium, and between the latter and the 

 stroma. Fig. 10, in my opinion, illustrates this very clearly, and notwith- 

 standing that the photograph was taken from a series through a sector that 

 was about ' 4 of the iris, I never came across a patch in this series that 

 was distinctly without dilatator; there were only some \ery narrow cracks 

 in the fibrillar la\er, as if it had cracked in the slicing or embedding pro- 

 cess. Fig. 10 gives rather the impression that the eye has had quite a well- 

 developed dilatator, and it shows also how 2 prominences push out into 

 the stroma. In the middle of one of these a small light patch is also seen, 

 and there can be little doubt as to their being strengthening fillets such 

 as Grynfeltt, Heerfordt and Forsm.ark have described. The upper one 



