2 



Anatomy. - "On the structure and the innervntlo)} of the iDiisetthis 

 sphincter pupilhie and the nnisciihis cHinris of the tiird's ei/e." 

 By Prol'. J. BoKKE. (With 12 figures). 



(Communicated in tlie meeting of April 23, 1915). 



Ill a former coniiniiiiication ') I described the innervation, the 

 rehitioiis between the inuscie-oells and the nerve-endings, of (lie ciliary 

 muscle of the human eye, as a type of plain muscular tissue. A 

 subsequent examination of frontal sections through the iris-muscles 

 taught me, that, as far as my preparations showed me, the relations 

 between the efferent nerve-endings and the muscle-cells of the sphincter 

 pupiliae in the iris of tlie Imman eye are essentially the same as 

 in the ciliary muscle. In connection with these observations it seemed 

 to be of interest to study somewhat more closely the structure and 

 the innervation of the intrinsic eye-ball-muscles (sphincter and dila- 

 tator pupiliae, ciliary muscles) of the bird's eye. 



For indeed, both from the physiological and the morphological 

 point of view, this comparison of the iris- and ciliary muscles of 

 mammals and birds seems to lie of interest. The swift and complex 

 accomodation (lens and cornea), tlie swift and varying play of the 

 muscles of the iris and their role in accomodation, the peculiar diffe- 

 rences in the function of the eyes in birds of diHeieiit kinds and 

 habits (birds of prey, fasttlying birds, day and night-birds, diving 

 birds etc.) make such a comparison of the details of the nerve-supply 

 tempting. And beside these physiological differences the ciliary and 

 iris-muscies of birds present such striking morphological characteristics, 

 that these alone would make a comparison of the avian and mam- 

 malian eye-muscles valuable. 



The intrinsic muscles of the avian eye, both the muscles of the 

 iris (with the exception of the dilatator pupiliae) and the ciliary 

 muscle, are distinguished from the homologous muscles of mammals 

 by their being composed of striated muscle-fibres, as was known 

 since the classical researches of Brücke and Mcller. 



In the vertebrate series this cross-striation of the inner muscles of 

 the eye-ball is only found in reptiles and birds. As was mentioned 

 above, it is met with both in the muscles of the iris and of the 

 corpus ciliare. Only the so-called dilatator pu|)illae of the membrane 

 of Bkuch, as it was shown by the interesting and thorough re.searches 

 of Grynfei.lt, Andreae, Zietzschmann, von Szily and others, does not 

 show any vestige of cross-striation. 



M Proceedings of the meeting of Jan. 30, 1915. Royal Academy of science, 

 Amsterdam, p. 982— 98'J. 



