336 CHAPTER XXV If. 



or by treating a negatively impregnated cornea with weak 

 salt solution or weak solution of hydrochloric acid (His). 



But the best positive images are those furnished by gold 

 chloride. RANVIER prefers his lemon-juice method. It is 

 important that the cornea should not remain too long in the 

 gold solution, or the nerves alone will be well impregnated. 



ZAWARSIN (Arch. mik. An at., Ixxiv, 1909, p. 116) removes 

 the membrane of Descemet for study in the following manner. 

 A cornea, fixed in sublimate, is dissected out and put for 

 some hours into a mixture of alcohol and ether. Then 

 collodion of 4 per cent, is poured on to the inner surface, 

 and after some time a layer of collodion with the membrane 

 attached can be peeled off, and the collodion removed from 

 the tissue by a mixture of alcohol and ether. 



See also ROLLETT, in Strieker's Handb., pp. 1102, 1115, or 

 previous editions TARTUFKRI, Anat. Anz., v, 1890, p. 524, or 

 previous editions ; CIACCIO, Arch. ital. Biol., iii, p. 75 ; and 

 RENAUT, C. R. Acad. 8c., 1880, p. 137. 



666. Crystalline. CIEBHARDT (Zeit. wiss. 1/VA 1 ., xiii, 1896, 

 p. 306) hardens the lens for one or two days in 4 to 10 per 

 cent, formalin; it is then easily dissociated with needles into 

 its fibres. 



RABL (Zeit. wis. ZooL, Ixv, 1898, p. 272) fixes the 

 enucleated eye for half an hour in his platinum chloride or 

 picro- sublimate, 75 and 70, divides it at the equator, and 

 puts the anterior half back for twenty-four hours into the 

 fixative. 



For Maceration you may use sulphuric acid, 541. 



See also ROBINSKI, Zur Kenntniss d. Augenlinse, Berlin, 

 1883. 



