484 NEUROGLIA AND SENSE ORGANS. 



( 47) with 1 of 7 per cent, sublimate solution, dehydrate with 

 alcohol followed by acetone, make paraffin sections, and stain in 

 saturated aqueous solution of Victoria blue heated till it steams ; 

 rinse with Gram's fluid, differentiate with xylol 1 part, aniline 2 parts, 

 and mount in balsam. Simple, applicable to lower animals, and 

 gives very sharp pictures. 



915. DA FANG'S Methods (Ricerche Lab. Anal. Roma ed altri Lab. 

 Biol., xii, 1906). Method I. is a modification of MALLORY'S phospho- 

 tungstic hsematoxylin process ( 913). 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 embedded in paraffin. 

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

 MALLORY'S method, and stained with an old solution of MALLORY'S 

 phosphotungstic hsematoxylin, but prepared without 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 ( 912). Very 

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

 of 2 volumes 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 embedded in paraffin. The sections, stuck to slides, are 

 successively mordanted for twenty-four hours each with WEIGERT'S 

 copper acetate-chromium fluoride fluid (910), 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 hsematoxylin method. 



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

 unsuccessful preparations made by CAJAL'S reduced silver method. 

 Pieces treated as by Cajal's formula la or one of its modifications 

 ( 837), or simply fixed in 2 or 3 per cent, silver nitrate at 36 to 

 37 C., are embedded 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. 



916. HELD'S Method for Marginal Neuroglia (Monatschr. Psych. 

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

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



