SPECIAL STAINS. 401 



are hardened for at least two or three months in Miiller's solution. They 

 are well washed with distilled water, and brought into a 0'5 to 1 per cent, 

 solution of chloride of zinc. This is changed for fresh every day for seven 

 to ten days (until it does not become yellower than bichromate solution). 

 Sections are then made, washed quickly with alcohol, imperfectly cleared 

 (see 779) with kreasote, and mounted in dammar. This process is said to 

 demonstrate better than Grolgi's the finer structure of ganglion-cells and 

 their processes. 



763. FLECHSIG (Arch. f. Anat. u. Phys., Physiol. Abth., 1889, p. 537 ; 

 Zeit. f. wiss. Mik., vii, 1, 1890, p. 71) has a process for combining Golgi's 

 impregnation with v. BEANCA'S redwood stain (ante, 694) and a gold 

 chloride impregnation, which seems to me too complicated to be trustworthy. 



764. MONTI (Atti d. R. Accad. del Lincei Roma, Rendic., v, 1889, 1 sem., 

 p. 705 ; Zeit. f. wiss. MiJc., vii, 1, 1890, p. 72) describes a brown impregna- 

 tion brought about by the combined action of bichromate of potash and sul- 

 phate of copper. The method does not appear to have been yet brought to 

 a practical form. 



)3. Special Stains. 



765. The most important of the methods for the study of 

 nerve-tracts, plexuses, and the finer relations of nerve-fibrils 

 and ganglion-cell processes are those that have already been 

 given in the last Chapter, together with some of those given 

 in this Chapter, and classed as general stains. 



As myelin stains we have the processes of Weigert, 688 

 and 703, and the modifications of the same by Max Flesch, 

 689 ; Benda, 690 ; Pal, 692 (very important) ; Schafer, 

 693 ; Kultschizky, 697; Wolters, 699, 700, and others; 

 and as processes less exclusively directed to the demonstra- 

 tion of the myelin element, and claiming more particularly to 

 serve for the demonstration of axis-cylinders and cell processes, 

 the chromate of silver impregnation methods of Golgi, 704 

 to 706 (of the highest importance, and of the widest applica- 

 bility), with the modifications of the same by Sehrwald, 708; 

 Greppin, 710 ; Obregia, 711; Ramon y Cajal, 714, and 

 others, amongst which I would particularly call attention to 

 the details of the process as carried out by Ram6n y Cajal ; 

 and amongst the others later described that of Wolters, 

 726, and the iodide of palladium method of Paladino, 

 727. 



There remain to be mentioned some other methods, based 

 for the most part on somewhat different principles. 



26 



