444 CHAPTKH 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. Opht'ialm,., xlv, 1898, p. 286; Zeit. wiss. 

 MiJc., xvi, 1899, p. 79), who finds that forrnol fixes the lens badly, the 

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

 cerned ; and HERZOG (Arch. inik. Anat., Ix, 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. 



KOLMER (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 (Vcrli. Ges. Naturf. JErzte, Ixxi Vers., ]900, p. 459) fixes in 

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

 hours in each. 



ZiJRN (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 Siiurefuchsin or Picro-Sanrefuch- 

 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 TARTUPERI 

 (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, he rolls the retina 

 (op. cit.j 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. Monatsschr. Anat. Phys., xxi, 1904, p. 393. 



