472 AXIS-CYLINDER AND DENDRITE STAINS. 



The method gives particularly good results with cerebral cortex 

 and Ammon's horn, very poor ones with the cerebellum and spinal 

 cord. It is superior to the silver method in so far that the reaction 

 can always be obtained with certainty in a certain time ; that the 

 preparation can be preserved by the usual methods ; that large 

 pieces of tissue can be impregnated. Moreover, it is cheaper and may 

 give a more abundant and finer impregnation than even the rapid 

 process. 



895. Modifications of GOLGI'S Bichromate and Sublimate Method. 

 MONDINO (Ztsch. wiss. Mikr., ii, 1885, p. 157) has obtained good results 

 from even whole human brain treated according to Golgi's original 

 method. 



FLATAU (Arch. mikr. Anat., xlv, 1895, p. 158) fixes whole human 

 brain in 3 to 4 per cent, potassium bichromate. After two or three 

 months slices ^ cm. thick and 1 to 2 cm. wide are brought into 0-1 

 per cent, mercury bichloride to be changed every two to three days 

 for the first three weeks or so. Pieces are ripe for cutting after nine 

 to twelve months, at which time they are washed and embedded 

 in celloidin. Sections are passed through alcohols, cleared in carbol- 

 xylol and mounted in balsam. 



PAL (Erratim " Tal ") (Ztschr. wiss. Mikr., iv, 1887, p. 497) converts 

 the whitish mercury impregnation into a black one by treating sections 

 with 1 per cent, sodium sulphide. They may then be counterstained 

 with Magdala red. 



GOLGI'S sublimate method may be combined with Weigert's myelin 

 stain (see PAL, Wiener med. Jahrb., N.F. 1, 1886, p. 619, and the abstract 

 of this paper in Ztschr. wiss. Mikr., iv, 1887, p. 92, in which EDINGER 

 pointed out that the mercury impregnation can be turned black by 

 treating sections with diluted ammonia). 



FLECHSIG (Arch. Anat. Phys., Physiol. Abih., 1889, p. 537) has pub- 

 lished a rather complicated combination of Brama's Guinea red-wood 

 process for medullated nerve-fibres and Golgi's sublimate method, as 

 slightly modified by Held. 



896. Cox's Process (Arch. mikr. Anat., xxxvii, 1891, p. 16). This 

 is the most important of all modifications of Golgi's bichromate and 

 sublimate method. Cox found that the sublimate and bichromate 

 can be used together, and that potassium chromate can be usefully 

 added to the mixture in order to reduce the normally acid reaction 

 of the bichromate, as otherwise axis-cylinders are not impregnated. 

 He used a fluid consisting of 20 parts of 5 per cent, potassium 

 bichromate, 20 parts of 5 per cent, corrosive sublimate, 16 parts of 

 5 per cent, potassium chromate, and 30 to 40 parts of distilled water. 

 To prepare it, the bichromate and sublimate are mixed together, the 

 chromate diluted with the water and added to the mixture. 



One generally uses small pieces of tissues, but also relatively large 



