GOLGI BODIES ETC. 311 



3. AVash in water, and fix on gelatin-coated slides with formalin. 

 See §§ 227 and 228. 4. Rinse in water to remove excess formalin, 

 mordant at 50° to 55° C. in chromic acid 4 per cent., osmic acid 

 2 per cent., equal parts, on slide for varying periods — fifteen 

 minutes to one hour, or longer, 5. Rinse in water and stain with 

 iron alum 3 per cent, for fifteen minutes, followed by \ per cent, 

 haematoxylin for fifteen minutes, at 50° C. Differentiate in the 

 cold in iron alum till the nuclei show pale brown. Transfer to 

 2 per cent, aqueous pyridin for two minutes, dehydrate and 

 mount in xylol-balsain. 



In specimens chromed for short periods the mitochondria alone are 

 visible, while in those chromed for a longer time the mitochondria stain 

 less well, while gradually the long Golgi elements appear in the best 

 chromed cells. In animal cells, too. Drew finds short chroming shows 

 the mitochondria, while it requires longer treatment in the chrome to 

 demonstrate the Golgi apparatus. This is our own experience with the 

 Golgi elements or " nebenkern batonettes " of Mollusea. 



704. J. A. IMirray's Chrome-Osmic Method for Mitochondria 

 and Bacteria * of Mammalian Tissue. Fix tissue in formol-salt or 

 formol-Miiller overnight. Thin slices are then placed in Miiller's 

 fluid for from two to seven days, and then transferred to 2 per 

 cent. OsO^ for two days more. Wash overnight in running 

 water, dehydrate, imbed in paraffin. Sections to be not more than 

 5 /M, thick, fixed on slide, and stained in 3| per cent, iron alum 

 at 50° C. for fifteen minutes, followed by \ per cent, aqueous 

 ha^matoxylin in same way and for same time. Sections should 

 now be jet black. If such sections be decolourised in the ordinary 

 way in iron alum, both niitochondria and bacteria (if present) 

 will retain the stain, and nuclei are decolourised. 



If such sections are decolourised in 0-5 per cent. HCl in 70 

 per cent, alcohol, the mitochondria give up the lake and the 

 bacteria remain deeply stained. At the same time the details 

 of the nuclei are sharply stained. Wash sections for twenty 

 minutes in tap-water, counterstain in Van Gieson, mount in 

 balsam (Report Imp. Cancer Research Fund, 1919). 



705. Double-Staining in Haematoxylin and Acid Fuchsin. It is well 

 known that different cell elements have varying powers of resisting 

 decolourisation or differentiation after iron alum or such haematoxylin 

 stains. Thus in a hermaphrodite gonad or during fertilisation it is 

 sometimes noticed that the mitochondria of the egg hold the haematin 

 lake much faster than those of the sperm or spermatogenesis stages. It 

 is possible in certain cases to make use of this fact for studying differen- 

 tially cell granules, etc. 



Fix tissue by some prolonged mordanting method, such as that of 

 Champy-Kull, or Regaud. Wash out well in running water and prepare 

 thin paraffin sections. Stain by some intense hajmatoxylin method, 

 such as that of Benda or Heidenhain ; differentiate the cell element 

 which you wish to be stained subsequently a red colour, till it looks 

 pale greyish under the microscope : wash well in water, and counter- 



* Compare § 1332. 



