414 THE CORNEA, BY ALEXANDER ROLLETT. 



I am unable, on account of the insufficient number of my 

 investigations, to give the limits of age at which in a given 

 animal the contour lines are still preserved in the layers imme- 

 diately adjoining the membrane of Descemet, and when these 

 can no longer be seen. It is, however, certain that the mark- 

 ings are not visible in the fully developed cornea of adult 

 animals 



Great care should be taken in the investigation of specimens 

 too long exposed to the action of water, or of silver preparations 

 that have become distorted, or decayed, or broken down, in all 

 of which illusory appearances of the most various kind may 

 occur. The appearances described by Hoyer are thus explained 

 by the progress of the development of the cornea, and are as 

 little in favour of the existence of cavities lined with flattened 

 epithelial cells as the rupture of the cornea by puncture 

 injections. 



A few observations must still be made on that part of the 

 matrix of the cornea in which we consider the corneal cavities 

 with their processes to be imbedded (interfibrillar part of the 

 matrix). Very little is known respecting the nature and 

 peculiarities of this substance; we must, however, regard it 

 as a continuously connected portion of the cornea, distributed 

 through it in a definite but not uniform manner. Its distri- 

 bution is primarily dependent upon the arrangement of the 

 fibrils and fasciculi of fibrils. If we conceive this interfibrillar 

 substance to be rigid and the fibrils to be removed, and if we 

 further imagine the protoplasmic network extracted from the 

 corneal cavities, the skeleton that would remain would consist 

 of this substance. 



This skeleton, however, has perfectly definite morphological 

 characters. If a vertical section be made with a sharp knife 

 through a perfectly fresh cornea resting upon a piece of cork, 

 and the two surfaces of the section be separated from one an- 

 other under water, we shall see numerous elongated cavities ; 

 and where these spaces (the interlamellar cavities of Henle) 

 exist, the fasciculi of fibrils are in less intimate contact than 

 in the bands of tissue which occupy the interstices between 

 the spaces. The cavities are occupied by the flat bodies of 

 the corneal corpuscles. But if we compare the length of the 



