s. HOLTH AND O. BERNER. M.-N. Kl. 



that the base of these epithelial processes had been shifted in a central 

 direction in relation to their point, which is left lying in the stroma. But 

 then one would have to imagine that these epithelial processes have origi- 

 nally grown straight out in the stroma, and this they cannot have done, 

 for they are often . so long that they would have gone right through the 

 iris and farther still, if they had grown straight on. This would have been 

 the case, for instance, with both those shown in tigs. 14 and 15. On the 

 other hand it must be remembered that if these epithelial processes owed 

 their existence solely to a chance proliferation, it is curious that I should 

 never have seen one that had taken it into its head to grow in a central 

 direction, in towards the pupil; but processes taking that direction I have 

 never seen. It has also been a puzzle to me why 1 have found these pro- 

 cesses only in the outermost periphery oi' the iris and never within the 

 "projections". It seems clear to me that they are the result of a disturbance 

 in development, but why this disturbance should manifest itself just at this 

 particular spot I cannot explain. The only possible explanation, I think, is 

 that these rpit/ic/inl processes arc to be regarded as rudhnents of analogous 

 attacluncnts of the dilatator iiuiscle such as I have shown in fig. 12, which 

 is taken from a normal eye. 



That this working hypothesis, which I formed in the course of my 

 study, is correct, is apparent, I think, from the following observation, which 

 I have often made when looking at my various series. Closely asssociated 

 with the "projections", I have often found a peculiar object, which resembles 

 a sharply bent "hook". I have shown one of these in the microphotograph 

 reproduced in fig. 16. These "hooks" almost alwa3's turn off in a peripheral 

 direction, and soon end, as they run out in a point. In the depigmented 

 sections it will be seen that they are surrounded by large quantities of 

 muscle, but in the non-depigmented series it can also be seen that they 

 are accompanied by numerous pigment-cells. The similarity to the conditions 

 in the previously-described "epithelial processes" is clearly apparent on com- 

 parison of figs. 14 and 15 with fig. 17. With regard to the epithelial process 

 in fig. 14, I also found round it small quantities of contractile fibrils, while no 

 such fibrils had developed round the corresponding process in fig. 15. It 

 is my opinion, therefore, that fig. 14 shows a transition-stage between the 

 conditions in fig. 15 and those in fig. 17; and I have been confirmed in this view 

 by finding — in a depigmented series in which there was one such sharp "hook", 

 very similar to that shown in fig. 17, in the very middle of the muscula- 

 ture — some few sharply-defined oval cells with a long nucleus and smooth 

 protoplasm. They thus resembled the elements in the front layer of epithelial 

 cells as shown in fig. 8; and I conceive the explanation to be that the 

 iridian epithelium at this place has proliferated and essayed to develop a 

 strong attachment for the dilatator muscle. The greater number of the 

 epithelial cells have been transformed into muscle-elements of the mesoder- 

 mal type, and have there developed a powerful musculature around this 



