TECHNIC. 445 



modified fibrin stain (vid. Technic). The iodo-iodid of potassium solu- 

 tion is the same (saturated solution of iodin in a 5% iodid of potassium 

 solution). Instead of the customary gentian -violet solution, a hot satu- 

 rated alcoholic (70% to 80% alcohol) solution of methyl -violet is made, 

 and, after cooling, the clear portion decanted off; to every 100 c.c. of 

 this fluid 5 c.c. of a 5% aqueous solution of oxalic acid is added. The 

 staining takes place in a very short time. The sections are then rinsed 

 and normal salt solution and the iodo-iodid of potassium solution poured 

 over them (5% iodid of potassium solution saturated with iodin), and 

 washed off with water and dried with filter-paper and decolorized in the 

 anilin oil-xylol solution in the proportion of 1:1. The reactions are 

 rapid, and the thickness of the section should not exceed 20 //. This 

 .method is best adapted to the central nervous system of the human adult ; 

 it has as yet not been sufficiently tested for other vertebrates. 



Mallory' 1 s Selective Neuroglia Fiber-Staining Methods. Fix tissues in 

 io/c formalin four days ; place in saturated aqueous solution of picric 

 acid four days ; place in 5% aqueous solution of ammonium bichromate 

 four to six days in warm oven at 38 C.; dehydrate and imbed in cell- 

 oidin ; sections may be stained in Weigert's fibrin stain and differenti- 

 ated with equal parts of anilin oil and xylol, or they may be treated as 

 follows: Place sections in 0.5% aqueous solution of permanganate of 

 potassium twenty minutes ; wash in distilled water one to three minutes ; 

 place in i f/ aqueous solution of oxalic acid thirty minutes ; wash in dis- 

 tilled water ; stain in phosphotungstic-acid-hematoxylin solution (hemat- 

 oxylin i g., distilled water 8oc.c.,io^ aqueous solution of phosphotung- 

 stic acid [Merk], 20 c.c., peroxid of hydrogen [U.S. P.], 2 c.c.) for 

 twelve to twenty-four hours ; rinse in distilled water and place for five to 

 twenty minutes in an alcoholic solution of ferric chlorid (ferric chlorid 30 

 g., 30% alcohol 100 c.c.) ; rinse in distilled water and dehydrate quickly, 

 clear in oil of bergamot, and mount in xylol-balsam. 



jBendd's Selective Neuroglia Staining Method. Benda has for some 

 years concerned himself with perfecting selective staining methods for 

 differentiating certain constituents of the protoplasm of cells, and has 

 recently published a number of staining methods, by all of which neuroglia 

 fibers may be more or less successfully differentiated. According to him, 

 certain hematoxylin solutions, used after proper fixation and mordanting 

 of the tissues, may be used for neuroglia stains ; also hematoxylin staining, 

 followed by staining with an acid-anilin water crystal violet solution. 

 These will not be considered here. We wish, however, to call especial atten- 

 tion to the following method for staining neuroglia tissue, suggested by 

 Benda, since it has certain advantages not possessed by other selective neu- 

 roglia stains. Fix small pieces of tissue in 10% formalin; place in 

 Weigert's chrome-alum solution (formula given above), four days in warm 

 oven at 38 C.; wash in water twenty-four hours; dehydrate in graded 

 alcohols ; imbed in paraffin ; cut thin sections and fix these to slides with 

 the albumin-glycerin fixative ; remove paraffin and place sections in mor- 

 dant consisting of a 4% aqueous solution of ferric alum ; rinse thoroughly 

 in two tap waters and one distilled water ; place in a sodium sulphaliz- 

 arate solution (add to distilled water a sufficient quantity of a saturated 

 solution of sodium sulphalizarate in 70% alcohol to give it a sulphur-yellow 

 color) twenty-four hours ; rinse in distilled water ; stain for fifteen min- 

 utes in a o. i f /c aqueous solution toluidin blue, which should be heated after 



