10 GoldÌMg Biifl and Schäfer, 



aching the outer molecular layer, reach the lowest part of the fibrous 

 layer in the middle of this section, being here actually sessile upon 

 the outer molecular layer. 



4. The place of cessation of the ganglion -cell layer is at about 

 the same relative distance from the middle of the fovea as is shown 

 by all previous autliors who have described the region, excepting 

 W. Krause. In sections which do not pass accurately through the 

 middle this layer approaches the middle of the dip much more closely 

 than is the case in the section we have selected for representation. 



The appearance of the nerve -fibre layer on either side of the 

 fovea in this section is characteristic. On the one side, presumably 

 the inner, or that which is directed towards the entrance of the optic 

 nerve, the nerve-fibres are cut exactly longitudinally, upon the other, 

 or outer, exactly transversely. This may be taken to show that the 

 section passes precisely in a horizontal meridian or at least in the 

 meridian which includes the point of entrance of the optic nerve. 



Besides photographs (see PL I), which are of varying degrees of 

 magnification, we give a drawing from the central section which repre- 

 sents the middle and the adjoining part of the fovea magnified about 

 500 diameters (Fig. 4. p. 11). The drawing has been made in the 

 first place from a microphotograph, most of the elements of the several 

 layers as well as the general outlines having been directly traced 

 fi'om the photograph. The figure is so far schematized that where 

 the retinal elements are obviously artificially distorted they have been 

 represented in Ihe drawing as if not thus distorted, but their number, 

 their position, and as much as possible their actual size have been 

 rendered as accurately as possible so far as they were visible in a 

 single optical plane under the microscope. If the diagram is com- 

 pared with the photograph which is the most magnified of the 

 four (PI. I. Fig. 4), it will be seen that the main difference between 

 them is in the representation of the cones, especially of their outer 

 segments, which for some reason were not well preserved over the 

 very middle of the fovea photographed, and which were therefore 

 copied for the diagram from other preparations. On this account the 

 photogi-aphs themselves could not be taken as guides to the actual 



