GOLGI BODIES ETC. 317 



.3 drops of a 0-1 per cent, of pyrogallic acid is added, or else in a 

 modified Champy fluid. The following is recommended : — 



6 per cent, potassium bichromate 



1 per cent, chromic acid . . . . - 



2 per cent, osmic acid . . . .2 



2 c.c, 

 2 ,. 



Various other modifications have also been employed (see 

 Nassonow, Archiv.f. mikr. Anat., 1923, 97, 136—186, and 1924, 

 103, 437 — 482 ; also Weiner, Archiv. Russes d'Anat, d'Hist. et 

 d'Embrij., iv. 1925, 37 — -164). After twenty-four hours the 

 material is thoroughly washed (overnight), and then transferred 

 to 1 to 2 per cent, osmic acid at 30° to 35° C. for three to seven 

 days. Nassonow suggests the following method for determining 

 when the correct degree of impregnation is attained. Small pieces 

 of the tissue are broken off from the fragment in the warm osmic 

 acid. They are washed, and then mounted in glycerin. By 

 pressing on the coverslip the particles can be disintegrated, owing 

 to their brittle nature. In this way individual cells can be 

 examined under the microscope. When the material is found to 

 be suitably impregnated the fragments are washed in running 

 water, upgraded through the alcohols and imbedded in wax in 

 the usual manner. 



714. Ludford's Modified Mann-Kopsch Method. The tissue is 

 fixed in Mann's corrosive osmic fluid for eighteen hours. It is 

 then washed in distilled water for thirty minutes. Osmication is 

 carried out in an incubator at 30° C, using 2 per cent, osmic acid, 

 for three to fi\e days, depending upon the nature of the material. 

 The reduction process is completed by leaving the tissue for 

 another day in water at 30° C. The material is then brought up 

 through the alcohols and imbedded in paraffin wax {Jour. R.M.S., 

 1926, 107 — 109). Sections should be counterstained as described 

 § 710, page 314. 



715. Strength of Osmic Solution. Kolatchew used 1 or 2 per 

 cent, osmic acid, while otlier workers ihcluding Nassonow, Kopsch, 

 Morelle and Deineka all used 1 per cent. We have nearly always 

 used 2 per cent., but there has been a tendency nowadays to use 

 1 per cent., which in view of the cost of osmium tetroxide is more 

 economical. 



716. On Counter-Staining Weigl or Kolatchew Sections in Iron- 

 Alum Haematoxylin or Acid Fuchsin. The possibility of doing 

 this successfully should be noticed (see Gatenby and Beams, 

 Q.J. M.S., 1936). The advantage is that one can often get both 

 categories of inclusions stained in different colours. For example, 

 in spermatogenesis the Golgi apparatus will be black with osmic 

 acid, and the mitochondria blue with hcTcmatoxylin or red witli 

 acid fuchsin. This is sometimes very useful. The main difiiculty 

 is to hit off the time of bleaching properly. No exact times can 



