THE PROPER TISSUE OF THE CORNEA. 387 



plexus excellently attained with iodine vapour, and not only 

 are we able by means of control-researches with perfectly fresh 

 masses of protoplasma elsewhere obtained (mature and embry- 

 onal connective tissue), which may be examined whilst still 

 living, to give an explanation of the successive effects of iodine 

 in bringing the cell into view ; but we shall hereafter be able 

 to refer to this method for the decision of other moot points in 

 regard to the cornea. 



Let us now turn back to consider in greater detail, and whilst 

 quite fresh, the cells composing the cell-plexus of the cornea. It 

 has already been mentioned that when perfectly recent, they 

 are throughout so completely identical in their refractile power 

 on light with the matrix of the cornea, that it is impossible to 

 discover them under these circumstances. It is important to 

 know, however, that if the cornea has once commenced to lose its 

 perfect transparency, which gradually takes place when it is kept 

 under observation in a moist chamber, and immersed in aqueous 

 humour, the corneal corpuscles do not immediately lose their 

 vital properties. 



In point of fact, it is at this time that their contractility is 

 to be witnessed. The spontaneous changes of form under the 

 conditions in which they were seen by Kiihne,* and which, 

 according to his statements, are so deliberate that they can 

 only be demonstrated by a camera lucida, I have not been 

 able to observe. 



I must, however, substantiate the statement that induction 

 shocks of electricity are capable of producing contraction of the 

 corneal corpuscles. I must consequently take the part of 

 Kiihne, in opposition to Engelmann and others ; my descrip- 

 tion of the phenomena differing from his to a much less extent 

 than theirs. 



Experiments made elsewhere! induced me to try the effects of 

 applying a few powerful opening-induction shocks as a stimu- 

 lus. This was accomplished by the aid of a Riihmkorff's coil 

 (with a primary coil of 160 turns, iron core, and a secondary 



* LOG. cit., p. 125. 



t Golobew, Archiv fiir Mikroskopische Anatomic, Band v., pp. 55 and 

 56 ; and this Manual, pp. 41, 72, and 73. 





