312 GOLGI BODIES ETC. 



stain in Altmann's acid fuchsin. Extract the fuchsin to the right stage 

 in 95 per cent, alcohol, quickly dehydrate and clear in xylol ; mount in 

 balsam. If necessary, after staining in acid fuchsin, you may apply 

 the picric acid of Altmann's method (§ 694), but this necessitates under- 

 differentiation in the iron alum. 



We have found that after staining in the acid fuchsin you may 

 differentiate partly in aurantia as for the Kull method (§ 695). 



A method to be tried only by experienced cytologists. The difficulty 

 is to differentiate the hfematoxylin just to the right stage, and to avoid 

 washing away the acid fuchsin (Hans Held, Arch. f. mikr. Anat., Bd. 

 Ixxxix). 



706. On Post-Chroming and Post-Osmication in General. By 



soaking tissues in KgCrgO^, with or without CrOg, one produces 

 stainable compounds of cell proteins and lipoids which are not 

 easily dissolved out by alcohol and a clearing oil. One may 

 fix in almost any mixture not containing alcohol, chloroform 

 and acetic acid. Wash the tissue in aq. dest. for a short time 

 (say half an hour or less), cut into small pieces, and transfer 

 to 3 per cent, potassium bichromate for several days, and then 

 to 1 or 2 per cent. OSO4 for a day. Wash under tap overnight 

 and stain in Heidenhain or an Altmann. Thus tissues or embryos 

 fixed in special formol-chrome, corrosive formol, chrome-corrosive, 

 and other mixtures, which one has found most suitable for one's 

 purpose, may be post-chromed, or post-osmicated as well. 

 Schridde's and Murray's methods (above) inchide both post- 

 chroming and post-osmication. 



707. A. C. Hollande's Chondriome Method. Fix small pieces in 

 Benoit's fluid for four hours (uranium nitrate 4 per cent, aqueous, 

 4 parts ; potassium bichromate 5 per cent, aqueous, 6 parts ; saturated 

 mercuric chloride in saline, 5 parts, 2 per cent. OSO4, 5 parts). After 

 fixation place for twelve hours in a 3 to 5 per cent, solution of formalin 

 in distilled water, then wash in ordinary water for twenty-four hours. 

 Upgrade, toluene, paraffin. The sections on the slide are treated with 

 xylol, then for five minutes in a mixture of equal parts of 96 per cent, 

 alcohol and sulphuric ether containing 5 per cent, collodion, down- 

 graded in alcohols, to distilled water. Stain in Altmann's acid fuchsin 

 for thirty minutes ; wash half to one minute in distilled water, then 

 five minutes in an 0-5 per cent, aqueous solution of phosphomolybdic 

 acid. Pass to a 1 per cent, aqueous solution of methylen blue for 

 ten to twenty minutes, distilled water for fifteen seconds, then differen- 

 tiate in 95 per cent, ethyl alcohol for one minute. Dehydrate in two 

 baths of amyl alcohol for five to ten minutes, then equal parts of xylol 

 and amyl alcohol — then xylol and balsam. Mitochondria red, proto- 

 plasm bluish-red or grey, collagen and certain cell granules deep blue, 

 chromatin grey, bluish or rose, nucleoli bright red. 



708. Kopscii's * Osmium Tetroxide Method {Sitzungherg. d. k. 

 preuss. Akad. d. Wiss. zu Berlin, 1902). Osmium tetroxide 

 solution will fix both fats and lipoids, and proteid substances. As 

 has been mentioned above, the various cell inclusions, such as 



* Referred to by some writers as the Prenant-Kopsch method. 



