SUBLIMATE 513 



preventing the formation of opaque precipitates, and allows of 

 mounting in the usual way without any danger of spoiling the 

 specimens. 



One proceeds thus : Sections of pieces imbedded in ccUoidin 

 are thoroughly washed in many changes of water, and then trans- 

 ferred for a few minutes into a photographic fixing and toning 

 bath to be prepared at the moment of using, as follows : — 



Solution A. 



Gold chloride . . . . . 1 gr. 



Distilled water ..... 100 c.c. 



For use take 50 c.c. of sol. A, 7 c.c. of sol. B, and 



40 c.c. of old combined bath. 



From the fixing and toning bath sections are transferred into 

 distilled water and again thoroughly washed ; they are then 

 slightly counterstained with an acid solution of carmine diluted 

 with some alcohol, dehydrated, cleared, and mounted in the usual 

 way. 



The elements stained by the method are : (1) Nerve-cells 

 with all their processes and ramifications. (2) Nuclei, which is 

 not the case with the silver process. (3) Neuroglia cells. But 

 the reaction in this case is far less precise and complete than that 

 obtained by the silver method. (4) Blood-vessels, and particularly 

 their muscle fibre-cells. 



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 prei^aration can be preserved by the usual 

 methods ; that large pieces of tissue can be impregnated. More- 

 over, it is cheaper and may give a more abundant and finer impreg- 

 nation than even the rapid process. 



1042. Modifications of Golgi's Bichromate and Sublimate Method. 

 MoNBiNO (Ztsch, wiss. Mikr., 11, 1885, p. 157) has obtained good results 

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

 method. 



Flatu (Arch. mikr. Anal., 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 imbedded 



VADE-MECUM. 17 



