134 E. A. SCHAFER, 



cells of the tissue — the corneal corpuscles — contained in special 

 cell-cavities, which are flattened conformably with the lamellae, 

 and which serve in sections of the cornea to indicate the limits 

 of adjoining lamellae. Comparing with bone, we find in the 

 latter also layers of fibres united by a homogeneous ground- 

 substance, in which are seen between the several layers cell- 

 cavities or lacuna? containing the cells of the tissue flattened 

 conformably with the layers between which they lie. A further 

 analogy of structure is to be found in those fibres which in the 

 cornea pass obhquely, uniting layer to layer ; more especially 

 the almost vertical " binding '' fibres which pass through the 

 superficial lamellae towards the outer surface j for these, from 

 their position and general appearance, may without much effort 

 of the imagination be looked upon as representing the perforat- 

 ing fibres of bone. 



The chief point of difference, leaving out of account the 

 chemical constitution of the two tissues, is to be found in the 

 fact that in the cornea the fibres in a lamella run in the same 

 direction, while in bone there are two sets of fibres which inter- 

 cross with one another and are generally fused together at the 

 places where they come in contact. There is, however, sufficient 

 in common in the structure of the parts to enable a close com- 

 parison to be made. Since in sections of the cornea therefore 

 we speak of the lamellae as being separated from one another by 

 the flattened corpuscles, and in this way define a lamella as a 

 layer of fibrillated bundles closely held together by a homoge- 

 neous ground-substance which also covers the surfaces of the 

 layer, so in bone we must similarly define a lamella as a layer of 

 reticulating fibres covered on both surfaces by a homogeneous 

 substance, which extends between the fibres. It is clear 

 that in each case the homogeneous substance will only be dis- 

 tinctly visible in sections across the lamellae ; in strip-prepara- 

 tions in both cases the lamellae seem almost entirely composed 

 of fibres. Further, since the corpuscles are in neither case 

 epithelioid, i.e., do not fit together by their edges after the 

 manner of epithelium-cells, gaps are left between the adjacent 

 cells, and these gaps are occupied by the homogeneous ground- 

 substance which serves to unite the lamellae to one another. 

 So that apart altogether from any special fibres that may pierce 

 the lamellae, or that may pass across from one lamella to another, 

 the lamellae are never entirely distinct from one another, which they 

 would be were the cells actually epithelioid ; as for example, is 

 the case with those covering the connective-tissue tunics of the 

 Pacinian corpuscles. They allow of being stri|)ped away from 

 one another in bone, in consequence of the presence of the cell- 

 cavities (lacunae) in strata between the lamellae, in the cornea. 



