496 NEUROGLIA AND SENSE ORGANS. 



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, 1905, p. 393. 



GOLGI'S sublimate impregnation (Cox's form) has also been 

 successfully employed by KRAUSE and RAMON. 



The bichromate and silver method serves for the study of the 

 fibres of Miiller and neuroglia cells, as well as neurones. Weigert's 

 neuroglia stain does not give good results. 



LENNOX (Arch. f. Ophthalm., xxxii, 1886, 1 ; Zeit. iviss. Mik., Hi, 1886, 

 p. 408) has used Weigert's hsematoxylin method. 



KuHNT(Jew. Zeit. Naturw., Bd. xxiv, 1890, p. 177) employs Pal's 

 modification. Similarly SCHAFFER (Sitzb. Akad. wiss. Wien., xcix, 

 1890, Abth. 3, p. 110; Zeit. wiss. Mik., viii, 1891, p. 227). These 

 methods give a differential stain of rods and cones. 



For the zonula and ciliary body see MA WAS, Arch. d'Anat. micr., xii, 

 1910, p. 103. 



94. Dissociation. For maceration preparations you may use 

 weak solutions (0*2 to 0-5 per cent.) of osmic acid for fixation, and 

 then macerate in 0-02 per cent, chromic acid (M. SCHULTZE), or in 

 iodised serum (M. Schultze), or in dilute alcohol (LANDOLT), or in 

 Miiller's solution, or (RANVIER, Traite, p. 957) in pure water, for 

 two or three days. THIN (Journ. of Anat., xiii, 1879, p. 139) 

 obtained very good results by fixing for thirty-six to forty-eight 

 hours in one-third alcohol, or in 25 per cent, alcohol, and then 

 staining and teasing. 



SCHIEFFERDECKER macerates fresh retina for several days in the 

 methyl mixture, 543. 



KRAUSE (Intern. Monatsschr. Anat., i, 1884, p. 225) recommends 

 treatment for several days with 10 per cent, chloral hydrate solution ; 

 the rods and cones are well preserved. 



Inner Ear. 



> 925. Inner Ear, Dissection. For the dissection of the human ear see 

 POLITZER, " Die anatomische u. histologische Zergliederung d. men- 

 schlichen Gehoroganes," Stuttgart (Enke), 1889 (Zeit. wiss. Mik., vii, 

 1890, p. 364). Amongst the lower mammalia, the guinea-pig is a 

 favourable subject, as here (as with some other rodents) the cochlea 

 projects freely into the cavity of the bulla, and may be easily removed 



