296 TEGUMENTARY ORGANS. 



The cells are, however, visible, being recognisable by their 

 granular appearance and pale yellow tint. 



RENAUT (Comptes Rend., 1880, l r sem.,p. 137) gives the fol- 

 lowing process for corneal corpuscles : Cornea of frog. 

 Formic acid, 20 per cent., ten minutes ; gold chloride, 1 per 

 cent., twenty-four hours; formic acid, 33 '3 percent., twenty- 

 four hours. 



625 Cornea, Other Methods (ROLLETT, Strieker's Handb., p. 

 1102). Rollett strongly recommends the following plan: A 

 fresh cornea is placed (in humour aqueus) in a moist chamber, 

 and exposed to the action of iodine vapour. As soon as it has 

 become brown the epithelium may easily be peeled off. If the 

 reaction is not complete the cornea may be put back into the 

 iodine chamber. When sufficient iodine has been absorbed 

 the preparation may be examined, and it will be found that 

 the network of corneal cells is brought out with an evidence 

 hardly inferior to that of gold preparations. The method 

 never fails, which is not the case with the gold-method. It 

 is admirable as a fixing method. 



For dissociation of the fibres Rollett recommends macera- 

 tion in a solution of permanganate of potash or a mixture of 

 this solution with alum. As soon as the tissue has become 

 brown it is shaken in a test-tube with water, and breaks up 

 into fibres and bundles of fibres. 



Cell-division in the membrane of Descemet (see SCHOTT- 

 LANDER'S methods, ante, 610). 



626. Crystalline (Hardening of) (LowE, Arch.f. mile. Anat., 

 1878, p. 557). A fresh bulb is placed in a vessel containing 

 several litres of 1 per cent, bichromate of potash solution, 

 which is frequently changed for stronger solutions until the 

 strength of a cold-saturated solution is attained. The bulb 

 must remain in this for at least a year and a half, in order 

 that the crystalline may attain the right degree of hardness. 



627. Crystalline, Maceration. "Use Max Schultze's sulphuric acid 

 solution, supra, 518. 



Tactile Hairs. RANVIER (Traite, p. 914) recommends 

 for the study of the nerve-endings the boiled formic-acid ;m<l 

 gold-chloride method, 208. A tactile hair having been 

 isolated with its bulb, and its capsule incised, is put for about 



