CHAPTER XXIX. 375 



of the solution, in which it is left in the dark for from four days to 

 one week, according to its size. On removal from the gold solution 

 it is washed for a few minutes only in distilled water. Reduction 

 is effected by placing the pieces in a 20 per cent, solution of caustic 

 soda for four minutes, then rinsing in water and placing in a 10 per 

 cent, solution of potassium carbonate for from half an hour to an 

 hour. This is then drained off, and the pieces are placed in a 10 

 per cent, solution of potassium iodide for a short time usually 

 five to ten minutes. As soon as seen to darken, the pieces are removed 

 from this solution to water, placed in gum for twelve hours, and 

 sections cut on the freezing microtome. 



After dehydration the sections are mounted in camsal (propylic) 

 balsam. 



776. VIVANTE (Intern. Monasschr. Anit. u. Phys., ix, 1892, p. 398) 

 impregnates portions of frontal bone ot four to six months calves, which 

 are not more than 3 to 4 millimetres thick, by Golgi's rapid bichromate 

 and silver process. After impregnation the specimens should be 

 decalcified in von Ebner's mixture ( 562), well washed with water, and 

 brought into solution of carbonate of soda, and finally imbedded in 

 paraffin. For his quinolein blue method see fourth edition. 



For UNDERWOOD'S gold process for teeth, and for that of LEPKOWSKI, 

 see third edition, or Anat. Anz., 1892, p. 294. 



LAW (Proc. Eoy. Soc. Med., i, 1908, p. 45) studies nerve-endings in 

 teeth of mammals by treating paraffin sections of decalcified tissue with 

 BETHE'S molybdenum toluidin blue (details in Journ. Roy. Micr. Soc., 

 1908, p. 518). 



VAN DER STRICHT (Carnegie Instil. Embryol. Contrib., No. 21) 

 fixes the isolated cochlea in a 5 per cent, aqueous solution of tri- 

 chloracetic acid, or in Bouin's or Zenker's fluid, and stains, before 

 imbedding, in borax-carmine. The sections are afterwards stained 

 in iron-hsematoxylin, Congo red and light green. He obtained the 

 best results with the membrana tectoria by making one or two 

 openings in the bony wall of the fresh cochlea and exposing the 

 piece for fifteen minutes to the vapours from an aqueous solution of 

 osmic acid or by submerging it in a 1 per cent, solution of the same 

 for one hour. Afterwards fixation was completed by immersion 

 in trichloracetic acid, Bouin's fluid or Zenker's fluid, and the series 

 of sections therefrom stained as above. By this method some of the 

 turns of the cochlea give very good preparations of the structure 

 of the membrana tectoria. The mitochondria are also visible 

 within osteoblasts, osteoclasts, connective-tissue cells, all epithelial 

 cells, and the sensor ial elements. 



Mitochondria in odontoblasts and osteoblasts may be demon- 

 strated by fixation in Flemming-without-acetic followed by staining 



