H 



s. nOI.TH AND O. HKKNEK. M.-N. Kl. 



irises, from persons '>{' all ages, i began to try Aliieri's method on the 

 iris itself and not on tlic sections. For this purpose I cut out the iris 

 after it had been carefully fixed in ordinary formalin, and allowed it to 

 lie for 24 hours in a solution of potassium permanganate, i in 300. and 

 then in a V2 — i P^r cent, oxalic acid solution until bleaching had taken 

 place. The material thus depigmented was then imbedded in paraffin and 

 cut in serial sections of 5 </, and stained with iron hsematoxylin à la Heiden- 

 hain and with eosin as the protoj^lasm dye. 



As this method gave me much better preparations than those I had al- 

 ready obtained from my celloidin material from the eyes sent to me, I tried 

 it also upon these. I cut small pieces out of the block, and either com- 

 pletely removed the celloidin before proceeding with the bleaching, or left a 

 very thin membrane of celloidin round the material, thinking it would act 

 as a support for the epithelium during the depigmentation. Both modes of 

 procedure gave me good results, and the superiority of the method to the 

 usual depigmentation of single sections is, of course, obvious. The sections 

 made were both the ordinary meridional or radial, in which the dilatator 

 pupillae is seen cut longitudinally, and the so-called "tangential" sections, 

 where the muscle is cut across. Salzmann calls the latter "transversal", 

 which is a better name than tangential. In both cases the plane of the 

 section is perpendicular to the surface of the iris. As the iris, while being 

 imbedded in paraffin, is very liable to crumple, I also frequently obtained 

 such very oblique sections that they were equivalent to surface sections. 

 I have thus also been enabled to give figures of surface sections of the 

 small amount of dilatator that was obtainable in this case. 



The microscopical examination of the sections revealed no difference 

 between the two eyes, and I will therefore describe them together. 



The iris, as will be seen from fig. 6, is somewhat thin, with the excep- 

 tion of the central part, where the sphincter muscle is very distinct. This 

 may doubtless be naturally explained as due to a hypertrophy of the muscle 

 through being continually in a state of contraction as a consequence of the 

 loss of its antagonist. 



On examining the non-depigmented sections, I at once noticed that 

 the membrane of Bruch — or, as it is often called, the inner limiting 

 membrane — to a great extent was defective. In a ïew sections I found, 

 indeed, and especially with regard to the peripheral part of the iris, that 

 in front of the pigmented layer there was a red rim where the membrane 

 of Bruch should have been; but it extended only a little way, and was 



