290 THE RETINA, BY MAX SCHULTZE. 



which view the rounded cell forms occurring elsewhere certainly 

 constitute no objection. Kolliker* completed these observations 

 in so far that he directly states he has seen the gradual transi- 

 tion of the shortened radial fibres into the cells of the pars 

 ciliaris. He admits also the presence of a membrana limitans 

 interna at this part. On the other hand, we miss an exact 

 description of the isolated cells, the forms of which, as H. 

 Miiller has already pointed out, may, owing to the presence of 

 processes and dentations, be very various, and respecting which 

 Klebsf from his investigations admits that they pass directly 

 into the fibres of the zonula. Two regions, however, are to 

 be distinguished here, the smooth posterior and the plaited 

 anterior division, the plaits or folds of the latter forming the 

 processus ciliares. SchwalbeJ respectively designates these two 

 the zone of the orbiculus ciliaris and the zone of the ciliary 

 processes. He was able to isolate a limitans interna in both ; 

 but at the zone of the ciliary processes, after removal of the 

 vitreous, he found that it remains in part adherent to the zonula 

 Zinnii, especially at the points corresponding to the depressions 

 between the processes, which also remain covered with the 

 cells of the pars ciliaris retinae and the pigment, in consequence 

 of which the well-known form of the black-rayed zonula 

 originates. Schwalbe, however, does not, like Kolliker, con- 

 sider that the membrana limitans interna arises from the cells 

 of the pars c^iaris, but describes it together with certain reti- 

 cular externalVprocesses, observed also by Merkel, which extend 

 between the cells of the pars ciliaris, and correspond to the 

 radial supporting fibres as a prolongation of the connecting 

 substance of the retina. II By this means the transition of the 

 radial fibres of the retina into the cells of the pars ciliaris, 

 which Kolliker considered to be an ascertained fact, is again 

 rendered doubtful.^" 



* G-eivebelehre Aufl. v., p. 685. 

 t Virchow's Archiv, Band xxi. p. 187, 1861. 

 J Archiv fur Mikroskop. Anatomic, Band vL, p. 326. 

 Die Zonula ciliaris, Taf . i. , fig. 9. Leipzig, 1870. 

 IJ Ibidem, p. 303. 



^T See also the essay of Manfredi, Sulla struttura della parte cigliare 

 della Retina, in the Gaz. Med. Ital-Lombard, Ser. vi., Tom. iii., 1870. 



