390 THE CORNEA, BY ALEXANDER ROLLETT. 



be readily and completely followed by means of the iodine- 

 absorption method. It is consequently very expedient, besides 

 the researches on cornese ulcerated with nitrate of silver, or on 

 those which have been caused to inflame by transfixion with 

 a thread, also to institute experiments in which the- iodine 

 itself may act as a stimulus to inflammation. The freshly 

 decapitated and entire head of a Frog, after the membrana 

 nictitans has been excised, should be placed with a properly 

 made support in a large iodine chamber, and allowed to 

 remain till the cornese have assumed their full brown colour, 

 which occupies some hours after the removal of the anterior 

 epithelium. The excised cornea should be examined with the 

 addition of aqueous humour ; very remarkable appearances are 

 then presented. The nuclei of the corneal corpuscles will be 

 found to have lost their usual form, and to appear singularly 

 elongated, sinuous, and branched, and withal very smooth 

 and lustrous. Some of the nuclei appear deeply constricted 

 at one point, others have actually broken up into several 

 smaller roundish nuclei. The former obviously coincide with 

 those forms of nuclei that have been described by F. A. 

 Hoffmann* in inflamed cornese, and which he states resemble 

 migrating cells in all respects, and represent portions of the pro- 

 toplasm of the stellate cells which have become contractile. 



If we place a swathed and living Frog, from which the 

 membranse nictitantes have been removed, with its head in a 

 vessel containing moistened fragments of iodine, and thus 

 expose the cornese to the action of iodine vapour, a considerable 

 time usually elapses before the eyes become intensely stained, 

 and the excised cornese still assume a deeper tint when left 

 in the iodine cell. In the cornese of Frogs thus treated, the 

 transitional stages between corneal corpuscles and the migratory 

 cells may be very distinctly traced. 



In cornese ulcerated with nitrate of silver, which were ex- 

 amined in large numbers in the iodine cell, the images described 

 by N orris and Strieker were found to be, as already stated, 

 essentially accurate. We see, however, that in comese which 

 were as far as possible exposed to the same conditions, very 



* Loc. cit., p. 212. 



