Observations on the structure of the central fovea of the human eye. 3 



middle the cone-nuclei are shown as somewhat removed from the 

 limitans externa, but traced to the side they very soon come to lie 

 up against that membrane. The ganglion -cells are spherical. The 

 oblique direction of the fibres of the inner granules (bipolars) is clearly 

 indicated. Although no measurements are given of the diameter of 

 the fovea depicted, to judge by the stated magnification of the figure 

 its width is about 0-75 mm. and its depth about the same. The 

 section is expressly stated to be in the vertical meridian. The close 

 resemblance between the human fovea and that of the chameleon, 

 which has also been described by Hulke i) is specially insisted on. 



F. Merkel -) gives a figure and description of the central fovea 

 which seems to be based upon specimens so ill-preserved as to be of 



Fig. 1. Diagram of central fovea (M. Schultze). 



little use towards the elucidation of its structure. It is noteworthy 

 however that he also like Hulke, represents the external limiting 

 membrane as flat and the cones of the same length throughout. It is 

 here that we first find the ganglion- cells described as bipolar. 



The diagram of the structure of a section through the macula 

 lutea and fovea centralis of a human retina which was given in 1872 

 by Max Schultze in his article upon the retina ^) is almost too well- 

 known to need description, for it has been copied into nearly all text 



^) Journ. of Anatomy and Physiology. 1867. Vol. I. 



^) "Ueher die Macula lutea des Menschen etc." Leipzig 1870. 



^) Strieker's "Handbuch der Lehre von den Geweben". Leipzig 1872. This 

 diagram has a general similarity to two diagrammatic figures of sections through 

 the fovea, described by Schultze in Bd. II of the Arch. f. mikr. Anatomie, and is 

 evidently adapted from them; but it shows more than one not unimportant modi- 

 fication, as will subsequently be noticed. 



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