RETICULAR AND OTHER CONNECTIVE TISSUES 279 



three drops of 40 per cent caustic soda and the precipitate redis- 

 solved by adding ammonia drop by drop while stirring). 



3. Rinse quickly in distilled water and place in 20 per cent for- 

 malin for three minutes or till the sections dre black. 



4. Wash in distilled water and place for ten minutes in an acid 

 gold-bath (10 cc. distilled water to which are added 2 to 3 drops 

 of 1 per cent gold chlorid and 2 to 3 drops of glacial acetic acid). 



5. Immerse in 5 per cent hyposulfite of soda |-1 minute to re- 

 move all unreduced silver. 



6. Wash in distilled water, dehydrate, clear in xylol and mount 

 in balsam. 



Bielschowsky advised leaving tissues in the 20 per cent formalin 

 for 12 to 24 hours but as Maresh has shown this seems to be un- 

 necessarily long, at least when sections are used. To still further 

 shorten the process Woglom ('09, '10) has advised, for the purpose 

 of preventing shrinkage of the tissue, that the initial immersion 

 in 2 per cent silver nitrate solution need not exceed 5 minutes. 

 I have, however, found this time entirely too short in many cases 

 and its use led to much confusion in the interpretation of my early 

 results. In sections insufficiently impregnated the contrast 

 between collaginous and reticular fibers was not sharp, either the 

 reticulum taking a brown instead of a proper black color in lightly 

 toned preparations or if the toning was intensified many of the 

 collaginous fibers became a greyish black instead of the proper 

 golden brown. Moreover, I did not find troublesome shrinkage 

 of tissue in well fixed preparations. I would therefore advise 

 a strict adherence to the 12-24 hour period of immersion recom- 

 mended by Bielschowsky and Pollock ('04), Levi ('06) and others, 

 rather than the shorter period advocated by Woglom and, with 

 reservations, by Maresh ('05). 



In the lymphoid tissues the impregnation brings out most 

 distinctly the reticular fibers; they take on a deep opaque black 

 and stand out prominently against the golden brown of the collag- 

 inous fibers. The method has already been applied to connective 

 tissues and the assumption of a more or less specific staining 

 property for reticulum in the liver, lymphatic glands, tonsil, 

 spleen, ovary, and pleura has been casually recorded by Maresh 

 ('05), Ciaccio ('07), Magna ('08), Balabio ('08), Cesa-Bianchi 



