470 AXIS-CYLINDER AND DENDRITE STAINS. 



studying the inter-relationship between gland -ducts and gland-cells 

 (stomach, liver) if the silver chloride sections are afterwards stained 

 with thionin or toluidine blue or safranin, the sulphide sections with 

 Delafield's hsematoxylin, and the adurol ones with hsemalum or alum 

 cochineal. 



For toning, fixing and counterstaining sections of tissues treated by 

 the sublimate method and the like, see next paragraph. 



The Sublimate Method. 



894. GOLGI'S Bichromate and Sublimate Method (Arch. Sc. Med., 

 iii, 1878 ; Rend. R. Inst, Lomb. Sc. (2), xii, 1879, p. 205 and (2), 

 xxiv, 1891 ; Arch. Ital. Biol, op. cit., 880 ; Rif. Med., 1891 ; Opera 

 Omnia, I, p. 143, and II, pp. 505 and 607). For hardening, use either 

 a solution of potassium bichromate progressively raised from 1 to 3 

 per cent., or Miiller's fluid. It is best to take small pieces of tissue, 

 large quantities of hardening fluid, and change the latter frequently. 

 But the reaction can be obtained with much larger pieces, even 

 entire hemispheres. In this case the brain should at first be treated 

 with " repeated " injections of the fixing agent, or this should be 

 injected from the carotid or the aorta. Pieces, particularly if small, 

 begin to be ready for the subsequent treatment eight to ten days 

 afterwards, but it is advisable to wait until the twentieth or thirtieth 

 day of immersion, this being not injurious if prolonged for several 

 months ; it is, on the contrary, to be recommended if the pieces are 

 uncommonly large. 



When it is thought that the tissues have been hardened enough, 

 they are passed directly from the bichromate into -5 to 1 per cent, 

 mercury bichloride. One generally prefers weak solutions (0-5 per 

 cent.) if pieces have been left in the fixing fluid for a relatively short 

 period, having recourse to the stronger ones (1 per cent.) for materials 

 which have been hardened for many weeks or months. The subli- 

 mate solution must be changed at first every day, and later as often 

 as it becomes yellowish. At the end of the reaction pieces will be 

 found decolourised and almost with the aspect of fresh tissue. To 

 obtain a good reaction, about ten days of immersion in the mercury 

 bichloride are necessary if pieces are small, longer periods, and even 

 months, being required for large pieces and entire hemispheres. 

 Particularly fine results were obtained by Golgi from brains which 

 had been kept in 1 per cent, sublimate for as long as two years. 



The reaction may be said to have begun by the time tissues are 

 nearly decolourised. From that time onwards sections may be made 

 and mounted if successful. 



