514 GOLOI-COX 



in cello idin. Sections are passed through alcohols, cleared in carbol- 

 xylol and mounted in balsam. 



Pal (Erratum " 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. Abth., 1889, p. 537) has 

 published 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. 



1043. 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 ones can be employed, and whole brains of small animals 

 particularly if some of the fluid has been previously injected 

 through the carotid or aorta. The duration of the impregnation 

 is from two to three months, but material can be left in the 

 mixture for much longer, certainly without danger and, very 

 likely, with advantage. 



Mann {op cit.) recommends warming the mixture to the tempera- 

 ture of the incubator and diluting it to one-half the strength 

 advocated by Cox, particularly for material of adult subjects. 

 Portions of the brain measuring 1 cm. in thickness or entire brains 

 of young animals are placed by him on cotton-wool in this solution 

 and left in the incubator for twenty-four hours, when the solution 

 is changed. After a second change on the third day the vessel 

 (which should contain the mixture in proportion of 30 : 1 of 

 the brain) is sealed with vaseline and left in the incubator for 

 at least a month, but preferably for two. Da Fano finds this 

 way of carrying out the Golgi-Cox method very good, but, after 

 incubating for a month or so, prefers keeping the vessel at room 

 temperature, and cutting after another two or three months or 

 longer. 



There is considerable difficulty in making and preserving 



