444 CHAPTKli XXXV. 



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

 served as with solution of Miiller. 



See also Hippel {Arch. f. Ophthalm., xlv, 1898, p. 286; Zeit. wiss. 

 Mile, 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 Hbrzog {Arch. inih. Anai., Ix, 1902, p. 517, a.nd Encycl- 

 mile. Technilc, p. 75), who also approves of formol, but insists that it 

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



KOLMBR {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. 



Bbnda {Verh. Ges. Nahtrf. Mrate, Ixxi Vers., 1900, p. 459) fixes in 

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

 hours in each. 



ZtfEN {Arch. Anat. Phys., Anal. Ahth., 1902, Supp., p. 106) advises (for 

 mammals) fixinji; in saturated solution of sublimate in salt solution of 

 0'6 per cent., with 1 to IJ 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 vievi's I recommend iron- 

 liseniatoxylin, followed by Siiurefuchsin 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 Taetuferi 

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

 process. So also Ramon t 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., 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. Monat.suclir. Anat. Phys., xxi, 1904, p. 398. 



