180 



Ok a New Process of Histological Staining. 



By Frances Elizabeth Hoggan, M.D. 



{Read May 26th, 1876.) 



A description of the following histological process has already 

 been given in a paper which I read before the British Medical Asso- 

 ciation last year, at its meeting in Edinburgh. Although that paper 

 has been in the hands of the editor of the Journal for the last nine 

 months, it has not yet been published, but inadequate, and, in some 

 cases erroneous, accounts of my process, have been largely circulated, 

 especially in the continental scientific journals. Enquiries are still 

 often made of me respecting it, and I have, therefore, considered it 

 advisable to give, as shortly as possible, the details of this very 

 simple and effective process to your Society, whose members will, I 

 doubt not, put it to every variety of test. 



The tissues to be stained are principally mtmbranes or soft sec- 

 tions, which may be either fresh, frozen, hardened in alcohol, or 

 hardened by the picric acid and gum process, but such hardening 

 agents as the chloride of gold or any chromate whatsoever, are in- 

 admissible. 



The colouring agents required are : a 1 or 2 °/ solution of per- 

 chloride of iron in distilled water or alcohol (tincture of steel) ; 2, 

 a solution of similar strength of pyrogallic acid in water or alcohol, 

 the latter fluid being preferable in both cases. 



The section or membrane to be stained is first treated for one or 

 two minutes with alcohol ; the iron solution is filtered upon it, 

 allowed to remain for a couple of minutes, and then poured off. The 

 pyrogallic acid solution is then filtered in a similar way upon it, and 

 in the course of a minute or two, the desired depth of staining hav- 

 ing been obtained, the tissue is washed and may be mounted, in the 

 usual manner, either in glycerine, balsam, or varnish. 



The nuclei and nucleoli will be found coloured black, and the cell 

 substance will also be coloured more or less, according to the age 



