6 Golding Bird and Scliäfer, 



eyes, but the detailed description of only one of these is given. 

 Kulmt has not published figures of his preparations nor does he say 

 in what meridian liis serial sections were taken. He describes the 

 dip of the fovea as beginning 0*135 mm. from the middle which 

 would give a diameter of only double this amount (0-27 mm.) for 

 the whole fovea. In another place however he states that the 

 nerve fibres end as a distinct layer 0-4 mm. from the centre. As 

 according to the testimony of all observers they unquestionably end 

 witliin the dip this would give a total diameter of nearly 1 mm. for 

 the fovea. We do not know how the discrepancy between these state- 

 ments is to be explained. He describes the bottom of the fovea (over 

 an area which measures 0*2 mm. in a horizontal by 0'L5 mm. in a 



Fig. 3. Central fovea according to Schwalbe. 



vertical direction) as quite flat, and reduced to the cone and fibrous 

 layer. In the middle of this flat bottom (fundus foveae) is a minute 

 depression (foveola) which has only five or six cones over it in a 

 single plane of the section. Kuhnt further states that at the very 

 centre the cone-nuclei lie close to the limitans externa and in a single 

 layer and that their fibres radiate from this centre in a nearly hori- 

 zontal direction to either side (or rather to all sides). 



The illustrative deficiency of Kuhnt's paper is fiUed up by Schwalbe ^) 

 who represents a section through the central fovea and states that he 

 owes the figure and description to a preparation sent him for the 

 purpose by Kulmt. He adds "Leider zeigte sich an denselben das 

 Centrum der Fovea nicht genau getrofi'en, so dass ich Kuhnt's Angaben 



') Sinnesorgane. Erlangen 1887. p. 112. 



