172 



CONNECTIVE TISSUE. 



from the results of injections made by him and other recent observers into 

 the tissue of the cornea. Fluids, pressed into the corneal parenchyma, 

 produce, indeed, ramified figures resembling the " corneal corpuscles." W. 

 Kuehne, S. Strieker, and A. Eollett state that there are complete corneal 

 cells with protoplasmic bodies, with nuclei and nucleoli, within the ramifying 

 spaces, and that they fill these spaces completely. W. Engelmann denies the 

 existence of preformed spaces inclosing corneal cells, etc. He states that 

 there are spaces containing nothing but protoplasm, and this is, in my opinion, 

 the only correct view, as I shall endeavor to prove. 



In order to study the relation of the protoplasm to the basis-substance, I 

 chose the cornea of the dog and of the cat, giving preference, after repeated 

 trials, to that of the cat, as has previously been done by S. Strieker, on 

 account of its easy splitting. With some practice one may succeed in obtain- 

 ing lamellae which present two or even only one layer of corneal corpus- 

 cles, and which, therefore, are sufficiently transparent to admit of being 

 examined even with the highest powers of the microscope. 



FIG. 64. LAMELLA OF CORNEA OF A CAT, AGED ONE YEAR AND A HALF, 

 STAINED WITH A Two PER CENT. SOLUTION OF NITRATE OF SILVER. 

 Two LAYERS. [PUBLISHED IN 1878.] 



8, light fields with pale granular contents, faintly marked nuclei, and coarse and fine 

 processes. Every light field has perforated borders, and thus abundantly communicates 

 with a delicate light net-work which traverses the dark brown basis-substance, J3, in all 

 directions. Magnified 1000 diameters. 



To stain the cornea, I at first tried nitrate of silver. The cornea of a cat 

 was taken out immediately after death, and was put into a two per cent, 

 solution of nitrate of silver for one-half to one hour ; then it was washed with 

 distilled water, and, finally, for several days left under the influence of a very 

 mild dilution of acetic acid. Instead of the acetic acid, in later experiments, 

 I substituted lactic acid, which proved even more satisfactory than the 

 former. After being prepared in this way, the cornea of the cat was ready 



