CHAPTER XXVI. 325 



687. SOHRIDDE'S Method for Mitochondria, modified (Ergeb. Anat. 

 u. E. Merk. Bonnet, xx, 1911). Fix in this mixture : formol (1 part), 

 Miiller (9 parts), for two days ; then place in Miiller, two to four 

 days ; then 2 per cent. Os0 4 , for two days. Wash overnight, 

 dehydrate, clear in xylol, cut paraffin sections 5 /j. Stain as follows : 

 iron alum hot for a quarter of an hour, then hsematoxylin hot, 

 a quarter of an hour. Differentiate in alum in the cold. This 

 has the advantage over pure formol-chrome techniques in that the 

 introduction of the Os()4 preserves fat ; recommended by Duesberg. 

 With this mordanting it should be possible to stain either as for 

 Altmann, Bensley-Cowdry, Champy-Kull, or Benda. 



LEVI, G. (Arch. /. Zellf., Bd. xi), ovary of mammals. 

 10 c.c. . 2-5 per cent. K 2 Cr 2 7 . 



10 ,, . 5 per cent, sublimate containing 2 c.c. of formol. 

 2 ,, . 2 per cent. Os0 4 . 



Leave for three or four days. Wash out well in running water. Stain 

 in Regaud, Benda. etc. 



688. A. H. DREW'S Formol-Chrome-Haematoxylin Method (Journ. 



R. Micr. Soc., 1920). This method is used for demonstrating rod- 

 like bodies in the cytoplasm of plant cells. These rods are supposed 

 to be the homologue of the Golgi apparatus of animal cells. The 

 method will undoubtedly be useful for studying animal tissues. 

 Fix plant root tips, etc., for twenty-four hours in a mixture of 

 formol, 20 c.c. ; cobalt nitrate, 2 grms. ; sodium chloride, 0-8 grm. ; 

 water to 100 c.c. (preferably at temperature of 37 C.). Soak fixed 

 tissues in gum-syrup for at least an hour, and cut sections on freezing 

 microtome. Wash in water, and fix on gelatin-coated slides with 

 formalin. See 172 and 182. Kinse 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. Rinse in water and stain 

 with iron alum 3 per cent, for fifteen minutes, followed by ^ per cent, 

 hsematoxylin for fifteen minutes, at 50 C. Differentiate in the 

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

 2 per cent, pyridin for two minutes, dehydrate, and mount in xylol- 

 balsam. 



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 my own experience with the 

 Golgi elements or " nebenkern batonettes " of Mollusca. 



