CHAPTER XXVI. . 331 



cent. Os0 4 in water at 37 C. for several days as for Kopsch. Then wash 

 in water for several hours, dehydrate, embed and section. Mount 

 unstained, or cautiously treat in permanganate of potash or hydrogen 

 peroxide and then stain in acid fuchsin (Altmann) or iron haematoxylin. 



(6) Tissues may also be fixed as above, and then transferred to Alt- 

 mann's or Champy's fluid, and subsequently stained in Altmann's 

 fuchsin and picric acid. 



Cramer fixes wet films for about three minutes. We think that a 

 subsequent treatment o films as in above two paragraphs should be 

 useful. The main point to note is that substances in a tissue which 

 might be dissolved out or altered by the water added to the Os 4 

 crystals are fixed in situ, and without the danger of alteration. This 

 method should be of value to histologists and cytologists. 



696. SJOVALL'S Formol Osmic Acid Method (Anat. Hefte., Bd. xxx, 

 1906). 



Material fixed in formalin, but without chrome salts or platinum 

 chloride, may be, used for Sjovall's technique (Auat. Hefte., Bd. xxx). 

 Fix pieces of tissue or small embryos in neutral formalin (5 to 20 per cent, 

 neutralised with magnesium carbonate) for two days. Cut into smaller 

 pieces and wash in several changes of aq. dest. 



Transfer to 2 per cent. OsO^ solution for from two to fourteen days at 

 room temperature, as for Kopsch. Wash well in water, dehydrate 

 clear and embed. Cut sections 3yu,,il necessary decolourise in peroxide 

 ( 695) and mount unstained in balsam. 



This technique is capricious, much more so than Kopsch, and depends 

 firstly on a suitable fixation in formalin, and secondly on the right time 

 in Os0 4 : it is convenient to cut the tissue into several pieces, which are 

 removed from the Os0 4 at different intervals. At times SjovaJl demon- 

 strates mitochondria and not Golgi elements, and in all probability it is 

 not of such value as Mann -Kopsch. We consider that the method is of 

 use to the skilled cytologist, although it may not bg applicable for 

 geneial purposes. 



Note. Corrosive -formalin ( 112) and osmicated picric ( 100) may 

 also be used as preliminary fixers before a Kopsch or Sjovall osmica- 

 tion. We cannot recommend the latter, as the picric acid probably 

 introduces maceration ; the former is good. 



697. CHAMPY'S Iodide of Osmium Method (Jo urn. de VA-nat. et Phys., 

 xlix, 1913). Champy finds that osmium iodide prepared as below has 

 the power of blackening fat and certain other cytoplasmic inclusions 

 whose identity seems doubtful, but which he calls for the time being 

 catalyosomes or lyosomes. 



Just before use prepare the following solution : - 



Osmic acid 2 per cent. . . . .1 part. 

 Iodide of sodium 3 per cent. . . 1 ,, 



It produces a golden yellow colour. Place relatively large pieces of 

 tissue (5 to 6 millimetres) in the solution. If one takes very small pieces 

 as for the Kopsch techniques, one gets nothing but the osmic reaction 

 while the iodine reaction, which takes place deeper in, is masked. Leave 

 tissue in for at least twenty-four hours, and use a good deal of the liquid 



