444 CHAPTER XXXV. 



rangement of the parts. The retina lies flat, and is at least as well pre- 

 served as with solution of Miiller. 



See also HIPPEL (Arch. f. Ophthaim., xlv, 1898, p. 286; Zeit. wiss. 

 Mik., xvi, 1899, p. 79), who finds that formol fixes the lens badly, the 

 retina well, so far at least as the absence of folds from shrinkage is con- 

 cerned ; and HERZOG (Arcli. mik. Anat., lx, 1902, p. 517, and Encycl- 

 mil;. Technik., p. 75), who also approves of formol, but insists that it 

 should be acid, and adds 3 to 5 per cent, of acetic acid. 



KOLMEB (Arch. Gesammte Phys., cxxix, p. 35), fixes for twelve to 

 twenty-four hours in a mixture of 4 parts saturated solution of bichro- 

 mate, 4 of formol of 10 per cent., and 1 of acetic acid. 



BENDA (Vcrh. Ges. Naturf. Mrzte, Ixxi Vers., 1900, p. 459) fixes in 

 nitric acid of 10 per cent., and hardens in liquid of Miiller, twenty-four 

 hours in each. 



ZURN (Arch. Anat. Phys., Anat. Abth., 1902, Supp., p. 106) advises (for 

 mammals) fixing in saturated solution of sublimate in salt solution of 

 0*6 per cent., with 1 to 1| per cent, of acetic acid after removing the 

 anterior pole and the vitreous. Wash out in alcohol of 35 per cent, 

 made 5 per cent, stronger each day up to 50 per cent. ; then pass on to 

 stronger and cedar oil and paraffin. 



846. Staining.- -For general views I recommend iron- 

 haematoxylin, followed by Saurefuchsin or Picro-Saurefuch- 

 sin, or preceded by Bordeaux ; or Kernschwarz, followed by 

 safranin, or the Ehrlich-Biondi stain. 



The Methylen-blue intra-vitam stain has given valuable 

 results ; see the methods of DOGIEL. 



But the most important method is the bichromate- and- silver 

 impregnation of GOLGI, first applied to this object by TARTUFERI 

 (Intern. Monatsschr., 1887). This author employed the rapid 

 process. So also RAMON Y CAJAL (La Cellule, ix, 1893, p. 121) 

 with the double-impregnation process, 815. To avoid the 

 formation of precipitates on the tissues, he covers the retina, 

 before silvering, with a piece of peritoneal membrane, or a 

 thin layer of collodion. Or, better, lie rolls the retina 

 (op. cit., p. 130). After removing the vitreous, the retina 

 is cut away around the papilla with a punch or fine scalpel, 

 and separated from the choroid. It is then rolled up (after 

 being cut into quadrants or not), so as to form a solid block. 

 This is painted with 2 per cent, celloidin, which is allowed 

 to dry for a few seconds, and the whole is put into the 

 bichromate mixture, and further treated as a solid mass of 

 tissue. 



Ramon also employs his neurofibril silver method, see 

 Intern. Monatsttchr. Anat. Phys., xxi, 1904, p. 393. 



