6 



divides into two bninclies running at right angles to tlie motlier- 

 tibre, and thus Corming a radiating (ibre of the second system. The 

 curving round of the sarcostyles, the phice of these libril-lnindles in 

 tlie sarcoplasm, the whole aspect of the T-siiaped niuscle-iibre, drawn 

 in the tigure as accurately as possible, leave as it seems no doubt 

 as to the accuracy of tlie observation. And indeed, even CtKBkkg 

 as long ago as 1883, seems to have seen something like it, where 

 he says: "wo wir es, wie es so oft an unsereii Object der Fall ist, 

 uiit vielfach und mitunder senkrecht gegcn einauder sich verzweigenden 

 Miiskelfasern zu thnn liaben", . . . (I.e. p. 14j. 



Thus we must regard the muscular system of the iris in a certain 

 sense as a syncytium, composed of elements, connected with each 

 other, and in which the fibres of the circular system are in an 

 organic connection with the radiating fibres of tlie iris musculature. 



Entirely independent of this system remains the so-called memiu-ane 

 of Bruch, composed of fibres (or elongateil cells) runuing only in a 

 radiary direction and remaining through life in clo.se conneclion with 

 the epithelium of the iris, which do not show any vestige of cross- 

 striation, and to which must be ascribed exclusively, according to 

 ZiKTZscHMANN. the function of a real dilatator pupillae. 



In the muscular sheet of the iris of the human eye, being composed 

 of plain muscle-cells, this organic connection between the sphincter 

 muscle and the diiatatory fibres converging towards the pupil, is of 

 course not easily to be stated with accuracy. But the study of thin 

 tangential (frontal) sections through the iris gives one the impression, 

 that even here similar relations exist. 



In my former communication I described the interesting relations 

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

 the musculus ciliaris of the human eye. The small dimen.sions of 

 the muscular elements of the human corpus ciliare and the closely 

 interwoven nerve plexus make it very difficult to get a clear picture 

 of the numerical, relations between the nerve-endings and the muscle- 

 cells. The terminations of the efferent nerves seemed to be present 

 in two distinct types (compare ilie figures of the coininunication 

 mentioned above), as small rings or loops and as small networks, 

 but I could not get a distinct answer to the question whether these 

 two types of intraplasmatic nerve-endings belong to two different 

 kinds of efferent nerves or to nerve-fibres of the same kind and 

 the same source. 



Easier to determine are the relations between the efferent nerves 

 and the muscular elements in the bird's eye. 



