20 



S. HOI.TH ANI> O. I5K.K.NKR. M.-N. Kl. 



able about the stroma cells as regards either shape or pigment. In the 

 Heiclenhain-stained sections there were a good many large eosin-stained 

 cells with numerous fine, dark granules in the protoplasm. Nor was there 

 anything to remark with regard to the ordinary large, round pigment-cells 

 — the "clump cells". They generally occurred, as usual, in the sphincter 

 region. The blood-vessels, too, presented no peculiarities. Regarding the 

 appearance of the stroma I refer the reader to the various figures. 



We have thus shown that in these eyes the dilatator pupillae is defec- 

 tive in its development, and we must assume that the anomaly is due to 

 an inhibition that has asserted itself in embryonal life. This inhibition 

 does not seem to have affected that part of the dilatator that lies behind 

 the sphincter, for this, judging from the microscopical sections, is developed 

 normally. 



We have then all the developmental stages from this normal condition 

 down to the complete inhibition represented by the pure epithelium cells. 

 My investigations have shown further that the inhibition may be removed 

 locally^ and that strengthening bands may even be developed of the type 

 described by Forsmark. It will be remembered too, that Forsmark empha- 

 sises the fact that the strengthening bands are often very short and extend 

 only a little way between the region of the ciliary body and the periphery 

 of the sphincter. At the two places marked with a cross in fig. 6 there 

 seem to be fragments of strengthening bands such as these. 



Forsmark's work is of great merit, and has brought to light, among 

 other things, one or two deviations from the ordinary way in which the 

 dilatator elements appear. He has shown that an inhibition in the deve- 

 lopment of the dilatator sometimes appears, with the result that spindle- 

 shaped epithelial cells are found among the elements. He has further demon- 

 strated the "mesodermal type" of the dilatator elements. 



He has shown that the first type is often found in the periphery of 

 the dilatator near the ciliary body, and he describes it as "an intermediary 

 form between muscle and epithelial cells". The second t3'pe is found in 

 the strengthening bands, and always occurs when the dilatator elements 

 leave their place and move forward in the stroma. He calls it "mesoder- 

 mal" because its similarity to the ordinary cells of unstriped muscle else- 

 where in the organism is complete. 



I think both these types of cells are made clearer when placed in 

 relation to my material. As regards the first form the agreement with 



