72 ON THE STRUCTURE OF MUCULA LUTEA. 



most fresh state I could select, with a power of three hundred linear, 

 but could never arrive at a satisfactory result ; and, indeed, I usually 

 found the structure of the retina in the human eye, to be far less dis- 

 tinctly recognizable than in the eyes of animals recently killed. This 

 indistinctness of the objects I conceived to be attributable to the de- 

 composition which so speedily attacks the eye, since, in animals also 

 which have been two days dead, the structure of the retina is no longer 

 distinctly to be seen. The eye is decidedly that part of the body in 

 which traces of incipient decomposition first display themselves ; the 

 cornea in a few hours after death acquires a folded aspect, and the eye 

 appears as if it had lost a great part of its humidity. 



I recently had the opportunity, through the kindness of the Counsellor 

 of Medicine, von Treyden, to examine the eye of a man who had died 

 a few hours before of rupture of the spleen; the results of this in- 

 vestigation were so decisive as to afford me the greatest possible sur- 

 prise. 



The retina adhered SQ firmly to the vitreous humour, that it was 

 impossible to separate at least the greater portion of the latter, except 

 by actual cutting with scissors ; while, it is well known that soon after 

 death a fluid usually collects between the retina and the hyaloid 

 membrane, which renders the removal of the vitreous humour from the 

 retina extremely easy. It was already perceptible to the naked eye, 

 that the place of the yellow spot arose in a conical form, considerably 

 above the surface of the retina. The size of this elevation I was unable 

 to measure distinctly. I was, however, enabled, with a magnifying 

 power of three hundred linear, to perform one entire turn of the 

 screw of the micrometer, in order alternately to bring into focus the 

 highest point of the yellow spot, and the surface of the retina lying 

 beneath it. 



With the view of preserving the object as entire as possible, I did not 

 compress it strongly, but placed over it a very thin plate of glass a 

 quarter of an inch in size, in order to level the conical elevation. The 

 appearance which the yellow spot now presented most nearly resembled 

 the shagreen formerly used by stationers for the covers of cases, &c. 

 Elongated, rounded particles, gradually tapering towards the middle, and 

 about one-fourth or one-fifth the size of particles of marrow (markkor- 

 perchen), arranged themselves together with great regularity on the 

 remainder of the surface of the retina. They proceeded like radii 

 towards the periphery of the yellow spot, became larger at that point, 

 but less distant in their outline, and with them were associated the 

 marrow-like particles of the remainder of the retina, in "radual transi- 



