MICROCHEMICAL TESTS 289 



warm haematoxylin, and then to differentiate in the cold with acid 

 alcohol. Afterwards proceed to Hest's carnune. 



Paul Buchnek (Praktihum der Zellenlehre J., Berlin, 1915) fixes over- 

 night in a freshly-niade mixture of equal parts of absolute alcohol and 

 strong Flemming. Wash out for two days in 50 per cent, alcohol, 

 imbed in celloidin. stain in Best's carmine. 



672. Lison's Method. Lison (ibid.) states that contrary to general 

 opinion alcohol is not the best glycogen fixative. He recommends 

 especially for young embryonic tissues the following fluid : dioxan 

 saturated with picric acid 8-5 c.c., formol 1 c.c, glacial acetic 0-5 c.c. 

 He states that Bouin, or better, Bouin-Allen is excellent. It is curious 

 that in vitro picric acid does not precipitate glycogen, and Lison believes 

 that the action of the picric acid is to fix the glycogen on some substrate. 

 After Lison's fluid one could proceed straight into pure dioxan, then 

 dioxan wax. 



673. Bauer's Method. This method is probably the least specific of 

 all (see Bauer, Zeit. mikr. anrit. Forsch., xxxiii, 1933). It depends on 

 the fact that Schiff's reagent gives a violet colour with glycogen which 

 has first been treated with chromic acid. The method has been espe- 

 cially studied by Pasteels and Leonard, as reported by Lison. Fix 

 six hours in Bouin-Allen (adult tissue) or one hour (embryonic and more 

 delicate adult tissues), imbed through dioxan, section. After removing 

 the wax in dioxan, sections are treated in 4. per cent, chromic acid for 

 one hour, or overnight in 1 per cent, chromic. After chroming, the 

 glycogen is insoluble in water, and you wash under the tap for five 

 minutes, then ten to fifteen minutes in Schiff's reagent. Transfer to 

 three changes of SOj water as for the '" nuclealfarbung " method 

 (§ 623). Wash for ten minutes in running water, counter-stain the 

 nuclei as you wish, mount in balsam. Glycogen reddish-violet, but so 

 may be various polysaccharides, cellulose, starch, tunicin, etc. This is 

 an interesting method. 



SnuN IcHi Ono {Anat. Anthrop. Ass. of China, 1920) finds that 

 osmicated mitochondrial fixatives preserve glycogen, which can be 

 stained in Best's carmine and iron htematoxylin, the mitochondria 

 (grey-black) and the glycogen (reddish) showing side by side. 



See also Creighton, The Formative Property of Glycogen, London, 

 1896 ; Gage, Trans. Amer. Micr. Soc., xxviii, 1908, p. 203 ; Kato, 

 Arch. Ges. Phys., cxxvii, 1909, p. 125 ; Buscir, Arch. Intern. Phys., iii, 

 1905, p. 51 ; Mayer, Zeit. zviss. Mikr., xxvi, 1909, p. 513 ; Arnold, 

 Sitzb. Heidelberg. Acad. Wiss., 1909, p. 1, 1910, p. 3, and 1911, 14 Abh. ; 

 Arch. path. Anat., exciii, 1908, p. 175 ; Arch. mik. Anat., Ixxiii, 1909, 

 p. 265; Ixxvii, 1911, p. 346; Beitr. path. Anat., li, 1911, p. 439; 

 Fraenkel, Virchow's Arch., 1911, p. 197 ; Neubert, Beitr. path. Anat., 

 xlv, 1909, p. 38 ; Erhard, Arch. Zellforsch., viii, 1912, pp. 447 and 507 ; 

 Ehrlich and Lazarus, Die Anaemie, 1898, p. 30 ; Pekelharing, 

 Petrus Camper, Deel I, 1901, p. 231 ; Driessen, Zeit. wiss. Mik., xxii, 

 1905, p. 422 ; Fischer, Anat. Anz., xxvi, 1905, p. 399 ; Fiessinger, 

 C. R. Soc. Biol., Ixvi, 1909, p. 183 ; Neukirch, Arch. path. Anat., cc, 

 1910, p. 82. 



674. Iron. Organic compounds of iron, which are not ionisable 

 into ferric and ferrous ions, and in which the iron cannot be 

 detected by the ordinary reagents, are much more frequently 

 present in animal and vegetable tissues than was previously 

 believed to be the case. In addition to the albuminate com- 

 pounds, there exist iron compounds giving ferric and ferrous ions, 



TADE-MECUM. 10 



