510 OOLGI METHODS 



per cent, alcohol, and the sections transferred into fluid absolute 

 guaiacol and cedar-wood oil as already described in § 1027. 



Imbedding in paraffin is also possible, but results are usually 

 rather poor, and one should have recourse to it only for special 

 objects, such as muscles (see Veratti, Mem. R. Inst. Lomh. Sc, 

 xix, 1902, p. 87). In any case tissues should be passed quickly 

 through the lower grades of alcohol, and remain only a few hours 

 in 95 per cent, and absolute alcohols. They should be cleared 

 with cedar-wood oil, as xylol and similar reagents may be injurious 

 to the silver impregnation. One should transfer pieces directly 

 into paraffin of as low a melting point as possible. According to 

 Brookover {op. cit.), cedar-wood oil should be used over and 

 over again, as it becomes saturated with silver nitrate. 



1040. Mounting. As pointed out in § 1027, Golgi preparations 

 do not keep well if mounted under a cover-glass in the usual way. 

 How and why this happens it is very difficult to say. Though an 

 elaborate discussion between Sehrwald {Ztschr. wiss. Mikr., 

 vi, 1889, p. 443), Samassa {ibid., vii, 1890, p. 26), and Fish {ibid., 

 viii, 1891, p. 168) has furnished the net practical result that 

 watery fluids should be avoided as much as possible during the 

 after-treatment, it is not clear why preparations should deteriorate, 

 when mounted under a cover-glass in thick cedar-wood oil or 

 neutral balsam ; while Mann {op. cit., p. 277) states, on the other 

 hand, that sections keep well if mounted under a cover-glass in 

 Price's No. 1 pure neutral glycerin. 



For these reasons the general practice is to mount sections 

 without a cover, either on ordinary slides or on cover-glasses to be 

 inverted for study over the aperture of a hollo wed-out wooden slide. 



If mounting under a cover is desirable, this should either be 

 raised free of contact with the slide by means of wax feet or the 

 like, or the balsam of the mount should be rendered perfectly 

 anhydrous by carefully heating it on the slide with the section 

 in it, until it immediately sets hard on cooling, when a slightly 

 warmed cover can be applied. This last method is also recom- 

 mended by Huber {Anat. Anz., vii, 1892, p. 587). B. Lee (see 

 previous editions) advises keeping the preparations uncovered 

 until the sections have become quite dry and the balsam, applied 

 from time to time in thin layers, quite hard, and then to cover 

 them with a warmed cover-glass, this being slightly pressed down 

 on the sections. 



Various processes have been devised for mounting Golgi's prepara- 

 tions at once under a cover, but none of them give really satisfactory 

 results. One should have recourse to them either for special objects, or 

 if counterstaining with carmine or haematoxylin, or by Weigert -Pal's 

 method, or the like, is particularly desirable. In this case one of the 

 following methods may be employed : — 



Greppin (Arch. Anat. v. Enhvick., Anat. Abth., Supp., 1889, p. 55) 

 treats sections for thirty to forty seconds (until whitish) with 10 per 



