NEUROGLIA AND SENSE ORGANS 541 



(Mallory's phosphornolybdic hccmatoxylin may also be used for 

 the stain, but it is less elective.) 



Greenfield (in Anderson's How to Stain the Nervous System, 

 E. and S. Livingstone, Edinburgh, 1929), uses this method for 

 celloidin sections of formalin fixed material. These are treated 

 with 5 per cent, mercuric chloride for half an hour, followed by 

 strong iodine for three minutes, and after a quick rinse in tap- 

 water, by 5 per cent, hyposulphite for three minutes. The 

 sections are then placed in |- per cent, potassium permanganate 

 for five minutes, washed quickly in tap-water and transferred to 

 5 per cent, oxalic acid for five minutes. They are then washed 

 in distilled water for ten minutes before being stained for twelve 

 to twenty-four hours in Mallory's phosphotungstic ha^matoxylin. 

 Differentiation in alcoholic ferric chloride is specially useful here. 



Kernohan {Am. J. Clin. Path., I, 1931, p. 399) also uses formalin 

 fixed material. He first washes fixed tissue for twenty-four hours in 

 running water, then places it for four days in Weigert's primary myelin 

 mordant and for two days in Weigert's secondary mordant (see §1057), 

 subsequently imbedding in paraffin. 



1087. Da Fano's Methods {Ricerche Lab. Anat. Roma ed aliri Lab. 

 Biol., xii, 1906). Method I. is a modification of Mallory's phospho- 

 tungstic haematoxylin process f§ 1085). Small pieces of fresh tissue 

 are fixed for twenty-four to forty-eight hours in a mixture of 72 

 volumes of pyridine and 28 of 50 per cent, nitric acid. After washing 

 for about six hours, the pieces are dehydrated and imbedded in paraffin. 

 The sections, stuck to slides by the albumen method, are treated as by 

 Mallory's method, and stained with an old solution of Mallory's 

 phosphotungstic haematoxylin, but prepared imthout the addition of 

 hydrogen peroxide. In order to increase the contrast between neuroglia 

 fibres (blue-violet) and the protoplasm of neuroglia cells (pink) Da Fano 

 dehydrates the stained sections in 95 per cent, alcohol to which a small 

 quantity of an alcoholic solution of eosin has been added. 



Method II. is a modification of Benda's process (§ 1085). Very small 

 pieces are fixed for thirty-six to seventy-two hours in a mixture of 2 

 voliunes of the fixing fluid used for Method I. and 1 volume of 1 per 

 cent, osmic acid. After washing for six to twelve hours, the pieces are 

 imbedded in paraffin. The sections, stuck to slides, are successively 

 mordanted for twenty-four hours each with Weigert's copper acetate- 

 chromium fluoride fluid (§ 1083), 2 per cent, chromic acid, and 2 per 

 cent, iron alum, rinsing in water before passing them from one into the 

 other mordant. They are lastly either treated and stained as by 

 Benda's alizarine-toluidine blue process, or as by Heidenhain's iron 

 haematoxylin method. 



Method III. was arrived at in an endeavour to make use of unsuccess- 

 ful preparations made by Cajal's reduced silver method. Pieces 

 treated as by Cajal's formula la or one of its modifications (§ 1011), or 

 simply fixed in 2 or 3 per cent, silver nitrate at 36° to 37° C, are 

 imbedded in paraffin. The sections, stuck to slides, are bleached by 

 Pal's differentiation method for myelin stain, and then mordanted and 

 stained as by Method II. 



1088. Held's Method for Marginal Neuroglia (Monatschr. Psyeh. 

 Neurol., xxvi, 1909 ; Ergdnzungsh., p. 360). Tissues are preferably 

 fixed by means of a modified Zenker's fluid consisting of Miiller's fluid 



