RELATION OF CORNEAL CORPUSCLES TO MATRIX. 403 



for a short time this requiring special testing in each case 

 in dilute solutions of nitrate of silver containing one part 

 by weight of nitrate of silver dissolved in from 200 to 

 800 parts of water, and then exposing them in water to the 

 action of light, the rapid action of direct sunlight appearing 

 to be essential for the production of thoroughly successful 

 preparations. 



Long exposure to the action of water before examination 

 must be avoided, since this leads to the appearance in sil- 

 vered preparations of various figures that are difficult to 

 explain. 



If the cornea be examined soon after the brown discoloration 

 has thus been quickly produced, white areas are seen in the 

 brown matrix, from which white processes extend in every 

 direction,* the processes anastomose with each other, and, on 

 the whole, appearances are produced which call to mind the 

 protoplasmic plexus of the corneal corpuscles, except that the 

 contour lines of the nodes and processes composing the plexus 

 are more saccular and not so straight as those of the plexus 

 brought into view by treatment with solution of gold. (Compare 

 fig. 384 with fig. 380, a.) 



The statement of His,f that the figures appearing in silvered 

 cornese agree in their form with the cells, is under certain circum- 

 stances quite correct. It is not, however, always so, J because the 

 protoplasm of the cells may wholly or partially detach itself 

 from the walls of the cavities. In view of our own observations 

 on the protoplasmic plexus, rendered visible by placing the 

 cornea in the sinus of the membrana nictitans, or in cells 

 saturated with watery vapour, or in solution of chloride of 

 gold, or by its exposure to the vapour of iodine, we cannot 

 regard as correct the statement that has been made to the 

 effect that, as a general rule, the silver figures do not coincide 

 with the stellate corneal corpuscles, merely because the latter 

 appear with but few branches in specimens examined in aqueous 



* His, Virchow's Archiv, Band xx., p. 207; and v. Recklinghausen, 

 loc. cit. 



f" Loc. cit., and Schweizerische Zeitschrift fur Heilkunde, loc. cit. 

 v. Recklinghausen, loc. cit. 



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