1922. No. 4. MIOSIS CONGENITA SEU MICROCORIA FAMILIARIS. 25 



this region. Future cases of this armmaly may possibly throw light 

 upon the matter, but this is of a very intricate nature, as is shown by its 

 history, into which I will not go. The controversy on the subject has 

 been due parth- to the fact that theoretic reasoning has been employed to 

 explain the morphological conditions, another reason being that the works 

 on the subject are from a time when the mesodermal type of dilatator was 

 still unknown. In addition to this there are evidently individual variations, 

 and the difficulty of forming an objective opinion upon these points is most 

 clearly apparent from the careful expressions of which Forsmark makes 

 use in this section of his work. As long as the conditions are no clearer 

 than they now are as regards the normal anatomy, it cannot be expected that 

 pathological anatomy, through a single observation, can contribute much to 

 the solution of the questions. I therefore confine myself to the statement 

 that in the present case the long connecting fibres are composed of plain- 

 muscle cells of the usual mesodermal type. They are visible even in fig. 

 18, and fig. 19 shows a muscle cell of which the long nucleus in the 

 centre, with its rounded ends, is very characteristic of this species of tissue. 

 If the question of the relationship of these fibres were to be determined 

 from these figures, one would say that the long connecting fibres in my 

 material belonged to the sphincter. 



The short connecting fibres, as will probably be apparent from the 

 photograph reproduced in fig. 20, are composed of cells with a short and 

 thicker nucleus, their protoplasm being also somewhat pigmented. The 

 elements in these fibres therefore resemble rather dilatator. Mv investi- 

 gations in this respect have led to a result opposite to that at which Fors- 

 M.ARK arrived. 



A peculiar feature of the long connecting fibres is the rather long 

 diverticula into which the sphincter draws the pigmentary layer. Fig. 17 

 is from a photograph that I have taken of one of them, and it shows how 

 the pigmentary layer is drawn far forward into the stroma, and that one 

 of the long connecting fibres is attached to the blind end of the diverti- 

 culum. In the sections, especially those that are depigmented it will be 

 seen that it is only the front layer, the muscle epithelium, that is thus dis- 

 placed, the back layer passes without change of direction. The diverticulum 

 may thus be compared in a way to a blind tube pointing with its free end 

 up to the sphincter (see fig. 21). Its periphery is always covered by con- 

 tractile fibrils developed from cells of which the rest of the protoplasm turns 

 towards the centre of the tube. The muscular mantle of the diverticulum 

 continues without interruption in the developed muscle of the dilatator 



